The Royals went 10-19 in May, thanks in large part to an offense that was among the worst in the American League. The pitching staff, after a flaming hot start however, was not blameless either, as Royal hurlers have struggled for well over a month now. While overall the team's pitching numbers have been trending downward for a long time, the Royals nevertheless posted a slightly better monthly ERA in May (4.41) than they did in April (4.78).
Before looking at the May splits, it's worthwhile to take a look at the starter/bullpen breakdowns for the entire season.
| IP | BAA | K/BB | ERA | |
| KC Starters | 341,1 | .274 | 2.17 | 4.77 |
| AL Average | 340 | .264 | 1.95 | 4.25 |
| KC Bullpen | 159.2 | .236 | 2.25 | 3.89 |
| AL Average | 168 | .247 | 1.91 | 3.77 |
There's a lot to digest there, and I didn't even include K/9 or HR data, for the sake of clarity. First, it looks like the starters are getting killed by BAA (bad defense?) because their control of the strikezone is surprisingly good, second-best in the AL in fact, behind only Oakland. The bullpen's K/BB number is also good, although only fourth best in the league, but they've also allowed fewer hits, contributing to a better ERA. Second, I'm stunned to see that the best Royal bullpen in decades has already fallen behind league average, a shocking development that does not reflect well on Trey Hillman's usage patterns, considering the number of good options he has to work with. Bullpen management is perhaps the area in which the manager has the most impact on a team's performance, and to this point, it would be hard to say that Hillman has done well there. In Hillman's defense (somewhat), the bullpen has been hit hard by the longball (18 allowed, fourth most in the league). Overall, the Royals rank 6th in strikeouts, rarefied air for a franchise that has spent most of the decade finishing somewhere between 12th and 14th, year after year.
Before we head-off to the land of individual performance (great wines there, by the way, but the roads are terrible) let's take a look at the staff numbers month by month:
| BAA | K/BB | K/9 | ERA | |
| Royals in April | .276 | 2.15 | 6.41 | 4.78 |
| Royals in May | .253 | 2.24 | 6.95 | 4.41 |
Again, since the beginning of April was so superb, I don't think anyone would guess that actually, the pitching improved across the board in May. One final note on the overall pitching numbers: the Royals have only allowed 10 unearned runs, which is one of the lowest totals in the AL. This either means the Royals have been lucky in how they've timed their errors or that the staff has actually been a tick better than some AL staffs who have hidden lots of bad pitching behind "unearned" runs. The Twins for instance, have allowed over 30 invisible runs, at least in terms of ERA.
Here are the May numbers for the starters, sorted by innings pitched:
| IP | K/9 | HR | WHIP | ERA | |
| Greinke | 39 (6 starts) | 7.85 | 5 | 1.28 | 4.38 |
| Meche | 37 (6 starts) | 7.54 | 5 | 1.14 | 3.65 |
| Hochevar | 36.1 (6 starts) | 6.19 | 4 | 1.49 | 4.71 |
| Bannister | 31.1 (5 starts) | 5.74 | 3 | 1.60 | 6.03 |
| Tomko | 29.2 (5 starts) | 7.58 | 7 | 1.25 | 6.37 |
| Davies | 5 (1 start) | 3.60 | 0 | 1.60 | 1.80 |
Gil Meche put in a very quiet, effective May, truly anchoring the staff, but his gains were offset by meltdowns by Bannister (although his nice Sunday start is obviously not in these numbers) and Tomko. Hochevar and Greinke were so-so, although I'm not quite sure how Greinke allowed so many runs, in spite of a lowish WHIP and decent strikeout numbers. Also, take a look at Banny's numbers: he's been striking out more guys than the mythology around him (and his detractors) would suggest. It's not as if he's 2004 Jimmy Gobble or anything.
And about that guy Gobble, here are the May reliever numbers, sorted again by IP:
| IP | K/9 | HR | WHIP | ERA | |
| Mahay | 12.2 | 5.68 | 1 | 1.58 | 2.84 |
| Soria | 12.1 | 9.49 | 1 | 0.97 | 2.19 |
| Ramirez | 11.0 | 9.82 | 0 | 1.55 | 6.55 |
| Nunez | 10.2 | 3.38 | 0 | 0.84 | 0.84 |
| Peralta | 10.2 | 5.06 | 4 | 1.03 | 5.06 |
| Gobble | 9.1 | 8.86 | 1 | 1.18 | 4.82 |
| Yabuta | 9.0 | 8.00 | 1 | 1.33 | 2.00 |
| Musser | 1.0 | 0.00 | 0 | 1.00 | 0.00 |
Wow, four homers allowed by Peralta, eh!?!? Was anybody expecting to see Ramirez's May ERA that high? Like a few staff pitchers, his overall ERA still looks low, because he logged all those 0.00 ERA innings to start the season. It's fairly clear that Ramirez torpedoed the pen this month, and the sooner Hillman realizes the league may be catching up to him, the better. Likewise, did anyone notice that Yabuta had a decent month? Or that Nunez, whom I sorta thought was fading -- posted a 0.84 ERA in May?
Baseball Prospectus keeps a stat called Leverage, which keeps track of how important the situations a reliever's usage have occurred in. Guess which reliever has the highest leverage score in Hillman's pen? Brett Tomko, of course. As for more used relievers, the leverage rankings go like this: Nunez, Soria, Ramirez, Mahay, Gobble, Nomo, Peralta, Yabuta and Musser. Ideally, at the end of the season, we'll see Soria #1 (not third) and possibly Mahay higher in the chain. For what it's worth, according to BP's numbers Yabuta, Gobble, Tomko and Peralta have all been below average relievers, and Tomko & Peralta have also been below replacement level. Oh, and Nomo, of course, but he's gone.
Lastly, a word about defense. BP's defensive efficiency stat rates the Royals as the 10th best defense in the American League, with a D-Eff of 0.699 , i.e., 69.9% of the balls in play have been turned into outs by the defense. The Rays lead the league at 72%. The Mariners are last at 68.2%. (Again, the closeness of these numbers should tell you something about the essential realities of the game: 30% of balls in play become hits, give or take a percent.) According to the numbers at the Hardball Times, the Royals have the second-worst defense in baseball however, just ahead of the Mariners.