Starting pitching was supposed to be the Twins' strength this season after Scott Baker, Kevin Slowey, Nick Blackburn, Francisco Liriano, and Glen Perkins came together as one of baseball's best young rotations last year, but they've collectively taken a huge step backward through two months. Blackburn and Slowey have lived up to expectations, but Baker and Liriano have been big disappointments while Perkins' strong start unraveled thanks to an elbow injury. Here's a look at the overall numbers:

TWINS STARTING PITCHING
 
YEAR     IP/G      ERA     SO9     BB9     HR9      AVG      OBP      SLG
2008      5.9     4.32     5.6     2.1     1.2     .283     .324     .443
2009      5.9     4.95     5.9     2.5     1.4     .280     .329     .462

If asked to compare this year's rotation to last year's version most fans would probably guess that the numbers are vastly different, but that's not really the case. Yes, the rotation's ERA has risen 15 percent, which is ultimately the problem, but within that Twins starters have been remarkably similar to 2008. They're averaging the same 5.9 innings per start as last season--which would no doubt shock a lot of people--and have allowed a .280/.329/.462 line that's pretty damn close to last year's .283/.324/.443.

Through two months this year's rotation has given up about 15 percent more walks and homers, which matches the rise in ERA. They've also struggled to limit big innings as hitters have seemingly bunched damage together more often, particularly against Baker and Liriano. More walks have led to a slightly higher on-base percentage, more homers have led to a slightly higher slugging percentage, and that extra damage coming in bunches has compounded the problems on the way to a 63-point rise in ERA.

All of which is a long way of saying that the rotation should improve over the next four months, although it's worth noting that Twins starters ranked just eighth in the league with a 4.32 ERA last year, so even last season they weren't "great" as much as "solid and young." While big innings and ugly ERAs make it seem like Baker and Liriano have totally fallen apart, using Expected Fielding Independent Pitching (xFIP) to strip away the impact of defense, bullpen, and luck paints a somewhat different picture:

xFIP                2008     2009
Kevin Slowey        4.14     4.43
Scott Baker         4.25     4.74
Nick Blackburn      4.55     4.90
Francisco Liriano   4.40     4.94
Glen Perkins        5.05     5.11

According to xFIP, the rotation's decline has been the result of everyone basically pitching 5-10 percent worse than they did last season, which is a notion that'll be impossible to accept for people who can't get beyond Baker and Liriano both sporting an ERA in the 6.00s. However, neither pitcher has been as bad as his ERA suggests and Liriano in particular has been hurt by some combination of bad luck and poor defense.

FRANCISCO LIRIANO
 
YEAR      SO%      BB%      GB%      LD%     LOB%      BIP
2008     20.3      9.7     41.6     18.1     68.9     .302
2009     18.9     10.6     38.5     20.9     63.2     .333

There's zero doubt that Liriano's performance has declined. His strikeouts are down seven percent, his walks are up nine percent, and he's given up 15 percent more line drives while inducing seven percent fewer ground balls. However, all of that isn't enough to take his ERA from 3.91 to 6.60. Liriano has also stranded just 63.2 percent of his runners while the Twins' defense has allowed a .333 batting average on his balls in play, both of which are among the worst figures in the AL and somewhat luck-based.

Plenty of people will be quick to blame Liriano for all of that, but in reality defense and luck play a huge role. For instance, in Liriano's last start against the Rays there were at least three instances where the entire outing would've been viewed far differently had a ground ball been converted into an out. But as has been the case in many of Liriano's starts, the balls in play found holes, innings got extended, more damage was done, and his ERA ballooned higher. Baker is a similar story, albeit with more homers.

Calls to remove Liriano from the rotation and replace him with Anthony Swarzak are being fueled by an over-reliance on ERA and lack of understanding about the nuts and bolts of pitching performances. Yes, Liriano has an ugly 6.60, but his 50-to-28 strikeout-to-walk ratio in 58.2 innings and other factors show that he hasn't been nearly that awful. Yes, Swarzak has a 2.08 ERA, but he also has a 6/6 K/BB ratio with an unsustainably amazing 98.5 left-on-base percentage and .205 average on balls in play.

If this were 1989 or even 1999 it might make sense to champion a rotation switch by saying, "Swarzak has a 2.08 ERA and Liriano has a 6.60 ERA." However, this is 2009 and thanks to the explosion of data and research we know enough about what makes pitchers effective that ERAs fail to accurately depict either performance. Whether you choose to conclude that Swarzak has pitched very well or been very fortunate, if he keeps performing like he has through two starts his ERA will be closer to 6.08 than 2.08.

While that's bad news for Swarzak, it's also good news for Liriano, Baker, and the rest of the rotation, which is likely to do a much better job keeping runs off the board for the final two-thirds of the season. Unfortunately the same isn't necessarily true for the bullpen, which has been about as bad as expected after general manager Bill Smith stubbornly refused to bring in the relief help that the Twins have so obviously needed dating back to the middle of last year. Here's how the primary relievers stack up:

                     IP     xFIP
Joe Nathan         19.1     3.15
Matt Guerrier      25.0     4.12
Jose Mijares       16.2     4.46
R.A. Dickey        30.1     4.99
Luis Ayala         22.2     5.00
Jesse Crain        14.2     5.61

Jose Mijares' call-up and Matt Guerrier's bounceback have patched a couple of the gaping holes, but they've both been merely mediocre as far as primary setup men go and the rest of the bullpen can't be counted on in anything resembling an important spot. Plus, while Joe Nathan remains one of the elite closers in baseball and by far the Twins' best reliever, he's frustratingly been allowed to face a grand total of just 75 batters in 52 games and is quietly looking slightly more human at the age of 34.

If last year is any indication Smith won't bother to bring in any veteran relief help at the trading deadline. Robert Delaney and Anthony Slama are good relief prospects who've consistently posted ridiculous numbers in the minors, yet the Twins just got around to promoting the 24-year-old Delaney to Triple-A yesterday and the 25-year-old Slama remains at Double-A. The Twins have been one good setup man short of a solid bullpen since Pat Neshek went down last May and there's no sign of that changing.

Absolutely dreadful production from three lineup spots has the Twins' offense ranked just eighth in the AL despite Babe Ruth-like production from Joe Mauer and Justin Morneau, whereas the pitching staff also ranks eighth in the league because the young starters have regressed while the shallow bullpen has unfortunately met expectations. I'm fairly confident that the rotation can turn things around, but the bullpen is going to need reinforcements to avoid remaining a clear weakness.

Joe Mauer and Justin Morneau were the two best hitters in all of baseball during May, combining to hit .386/.478/.773 with 20 homers, 16 doubles, 39 walks, 51 runs, and 61 RBIs in 30 games, yet despite getting Babe Ruth-like production from two spots in the lineup the Twins finished the month just 14-16. The Twins lost more than they won in May while out-scoring their opponents by 30 runs (168 to 138), which perhaps makes up for going 11-11 in April while being out-scored by 23 runs (116 to 93).

Through two months the Twins have scored 261 runs and allowed 254 runs, which would typically lead to being something like 27-25 instead of 25-27, but their run totals are skewed somewhat by the 20-1 thrashing they gave the White Sox on May 21. If the final score of that blowout win was 10-1 rather than 20-1 the Twins would've been out-scored 254 to 251 to more closely match their 25-27 record. Turn the 20-1 into 10-1 and the Twins would rank ninth among AL teams in both run scoring and run prevention.

In other words, the Twins simply haven't been a very good team through one-third of the season, which is a difficult pill to swallow given some of the outstanding individual performances they've gotten from position players. Morneau has been the best hitter in the AL through two months, Mauer was the best player in the world during May, and the Twins have also gotten good all-around play from Denard Span, Joe Crede, Michael Cuddyer, and Jason Kubel, yet the offense as a whole has been merely mediocre.

                      RAR                              RAR
Joe Mauer            27.0        Brian Buscher        -1.6
Justin Morneau       22.3        Nick Punto           -3.6
Joe Crede            14.7        Matt Tolbert         -6.0
Denard Span          13.9        Alexi Casilla        -6.9
Michael Cuddyer      12.7        Delmon Young        -12.2
Jose Morales          6.1
Jason Kubel           5.6
Brendan Harris        2.8
Mike Redmond          1.1
Carlos Gomez          0.7

RAR stands for Runs Above Replacement, which calculates how many runs someone was worth both offensively and defensively compared to a replacement-level player at the same position. For instance, through 52 games Morneau has been worth 22.3 runs more than a replacement-level first baseman, which ranks as the sixth-best RAR total in the league. Mauer is one of the five players with a better RAR than Morneau, checking in at 27.0 runs above a replacement-level catcher despite missing all of April.

Along with Mauer at No. 3 and Morneau at No. 6, Crede, Span, and Cuddyer are among the AL's top 30 in RAR and Kubel has also been very solid despite the high replacement level at designated hitter. Add it all up and those six guys have been 96.2 runs better than replacement-level players offensively and defensively through 52 games. Unfortunately the lineup has nine places rather than six, and the Twins have gotten horrible production from second base, shortstop, and one of the outfield spots.

Nick Punto was placed on the disabled list over the weekend with a groin injury, but not before he hit .187/.290/.211 in 150 plate appearances while playing mediocre defense. That performance was worth 3.6 runs less than a replacement-level shortstop and not surprisingly the Twins rank 12th in the league with a measly .587 OPS from the position. We've seen this before from Punto, who somehow racked up 536 plate appearances in 2007 while hitting .210/.291/.271 to rank among MLB's worst players.

As little as the Twins have gotten from shortstop, their second basemen have been even worse. In fact, no position in the league has been less productive than Twins second basemen, who've managed a hideous .477 OPS with poor defense. Ron Gardenhire would love nothing more than to ruin the Twins' ideal batting order by sticking a speedy, light-hitting, bunt-happy second baseman in the No. 2 spot, but even he can't ignore Alexi Casilla and Matt Tolbert combining for 12.9 runs below replacement level.

Unlike the middle-infield trio of Punto, Tolbert, and Casilla, Carlos Gomez's great glove in center field at least cancels out his awful hitting so the end result is basically a replacement-level player. His overall .220/.282/.310 line is awful, but Gomez has shown some signs of improved plate discipline, ranks as one of the elite defensive center fielders in the league for the second straight season, and deserves to be playing every day--whether in Minnesota or Rochester--after starting just 28 of 52 games.

Gomez offsets some of his terrible hitting with an excellent glove, but Delmon Young has been useless on both sides of the ball. In fact, at 12.2 runs below replacement level offensively and defensively he's been the single worst all-around player in the AL through two months. Young has hit .239/.282/.275 in 117 plate appearances, which is good for a .557 OPS. No other corner outfielder in the league with that much playing time has an OPS below .640.

Not only has Young failed to make any significant strides at the plate for the third straight season, he's actually regressed from last year's poor performance. Young was one of the most undisciplined hitters in baseball last season, but this time around he's struck out twice as often while drawing even fewer walks. Beyond that his power has gone from bad to non-existent as he's managed just one homer and one double in 109 at-bats while once again ranking among the AL leaders in ground-ball percentage.

Believe it or not, being the AL's worst-hitting outfielder only scratches the surface of Young's awfulness because he plays an offense-driven position that's home to many big bats and complements his lack of production at the plate with horrendous defense in left field. On a per-inning basis Young has been the second-worst corner outfielder in the league defensively behind only Jose Guillen and since joining the Twins last year Ultimate Zone Rating has him 23.1 runs below average on defense alone.

All of which is a long way of saying that Gomez has been bad, but the trio of Punto, Tolbert, and Casilla have been terrible and Young has been the worst player in the league. Simply replacing Young, Punto, Tolbert, and Casilla with even replacement-level players would have saved the Twins around 30 runs, which is the difference between trailing the Tigers by 4.5 games or 1.5 games. The good news is that foursome can't help but improve. The bad news is that Mauer and Morneau won't hit like Ruth all year.