Can the Rotation Keep This Up?


The White Sox have been on an absolute tear recently and in addition to sitting atop the A.L. Central, a third of the way through the 2012 season they are also only half a game behind Texas for the best record in the American League. The offense has been scoring plenty of runs, despite a few key members getting off to very slow starts, but today I want to examine the starting rotation, which has been possibly the team’s greatest strength so far (mostly on the strength of Peavy and Sale), and try to determine how likely that success is to continue.

Collectively, the White Sox starters are averaging 6.2 innings per start, 2nd in the American League, they’re working deep into games. Their BAA (batting average against) is a league leading .229, their WHIP is a league leading 1.18; they are not letting many runners on base.  Their K% is 20.6%, tied for 2nd in the A.L. 59% of their starts qualify as “quality starts,” also 2nd in the league. By Baseball-Reference’s version of WAR, they lead the American League by a comfortable margin.

I realize that is a lot of numbers to throw at you, a couple of which may be unfamiliar, but they should convey that the White Sox rotation has been one of the very best in baseball so far this season.

The five original members of the rotation have combined to start 50 of the team’s 54 games, and with John Danks expected back from his DL stint very soon, I’ll limit this examination to Danks, Jake Peavy, Gavin Floyd, Chris Sale, and Philip Humber. I will look at some key statistics for each of them, then examine each pitcher’s previous track record, and try to reach some conclusions about what might be expected from each as the season continues. A few thoughts/explanations for the numbers that follow:

Innings Pitched per Game Started: Going deep into a game not only means you’re probably pitching well, it also keeps the bullpen fresh.

ERA: Not the best way to look at a pitcher’s performance, because it doesn’t account for the park (a 4.00 ERA at PETCO in San Diego is very different from a 4.00 ERA at Coors in Colorado), among other things. It is familiar to all fans though. For those interested, there are a number of more advanced pitching metrics, such as FIP and SIERA that can give a more accurate look at a pitcher’s performance. None are perfect, but many are better than ERA.

K% and BB%: These reflect the percent of plate appearances that result in either a strikeout or walk. Obviously a high K% is good, whereas a low BB% is the goal.

LOB%: This is the percentage of base runners that are eventually stranded on base. Higher is better, the league average hovers around 70-72%, and studies have shown that the extent to which a pitcher can control their LOB% is limited. In other words, if a pitcher’s LOB rate is much higher or lower than league average, he’s probably been  lucky (or unlucky), and things will probably regress to the mean (move back towards the average) soon.

BABIP: Stands for “batting average on balls in play.” If a player hits a ball and it does not go foul, or into the stands for a home run, it is said to be “in play.” Those balls either become hits, or outs. Pitchers have some control over this, but not as much as many would believe. A pitcher consistently generating “weak contact” is largely a myth. Plus, even weak contact can lead to hits, the proverbial ground-ball with eyes, or dying quail. League average tends to be around .290-.295; any pitcher too far from that is likely to regress to the mean before much longer. It is also worth looking at his BABIP from recent seasons, and expecting his in-season number to regress toward that previously established level.

The White Sox starters (all statistics come from Fangraphs and are up-to-date through Monday, June 4th):









John Danks








Jake Peavy








Gavin Floyd








Chris Sale








Philip Humber








John Danks: Danks has been way off his career norms this season. His K% has consistently been around 18-20% his whole career before dropping to 12.6% this season and his BB% had been below 8% before climbing this season. Changes in these figures are less determined by luck, and more likely to speak to some sort of change in a pitcher. If shoulder woes were bothering Danks before he hit the DL, it might explain those dips in production. His LOB% has been 6th worst in the A.L., meaning he’s likely due for some improved luck there. It could be that his shoulder woes have thrown everything off. The big question for Danks is will he be 100% when he returns? If he is, the White Sox can expect better things from him than they saw in April and May.

Jake Peavy: Peavy’s K% is right in line with his career norm; his BB% is lower than his career figure, but identical to his 2011 number. His LOB% has always been a little above league average, and so his 2012 rate, while better than he’d previously done with the White Sox, is not unusual in the scope of his career. The .243 BABIP is almost certainly unsustainable, as his career figure was .286 entering this season, and less than one pitcher per year puts up a figure that low in the American League. Still, a moderate drop there would still allow Peavy to put up a great season. The question is health, can Peavy maintain it? The last time he threw even 120 innings was 2008, in San Diego. If he can stay on the mound, Peavy is very capable of pitching at close to the same strong level he’s begun the season at.

Gavin Floyd: Floyd’s K%, BB%, and LOB% are all right in line with what he’s done over the last three seasons, even if that ugly 5.32 ERA makes things seem otherwise. The biggest difference has been home runs; Floyd is giving them up at a substantially higher rate than in any previous season. Floyd is giving up more fly balls than he has in the past, which might be a sign of a changing pitcher, but that difference is small. The larger difference is in the percent of those fly balls that are turning into home runs. Can Floyd keep the ball in the park? This is another statistic pitchers have less control over than you might expect.  Floyd’s number was 9.7% over the last three seasons, but has shot up to 15.1% so far in 2012. That will likely improve and we should see better things from him over the rest of 2012.

Chris Sale: Sale has been dominant. He’s throwing the 6th most innings per start in the American League and he leads the league with a 2.33 ERA. He’s 2nd in K% and 3rd in WHIP. He’s got a good case for the A.L. Cy Young for the first third of the season. He’s only 23 years old and has the potential to be one of the best pitchers in baseball. All of that noted… he won’t keep this up. I should say he probably won’t keep it up, but I’d also be comfortable saying he almost certainly won’t.  Sale profiles as a high strikeout pitcher, but his current K% would be the highest A.L. rate since 2009. His LOB% would be the 5th best A.L. figure in the last ten years. His BABIP is close to forty points better than league average. Like Peavy though, some regression to the mean still leaves plenty of margin for Sale to be very good. My question is how many innings can Sale pitch this season? Many wonder if he can stay healthy, the White Sox temporary decision to move Sale back to the pen implies they have some questions about it too. Even if he stays healthy though, after pitching 33.2 innings in 2010 and 71 innings in 2011, how high can he go in 2012? Sale should fall off a bit, but he can still be very good, I’m just not sure for how many more innings.

Philip Humber: Humber’s perfect game has been the highlight of the season, but aside from that he’s been a mess. There isn’t really a track record to look at, as despite making his Major League debut in 2006, Humber had only pitched 214.1 innings before this year. If anything, he’s actually been a bit lucky with his BABIP. His BB% has jumped quite a bit from 2011, and more walks tend to lead to a decreased LOB%, which Humber has also got this year. We know how good Humber can be, but consistency is a difficult trick, and Humber hasn’t shown any so far. Can Humber cut back on the walks? If he doesn’t, the perfect game may be just about the only positive take away from his season. Humber is 29, not some kid. I’m not sure Sox fans should expect much better results from him the rest of the way.

I’m expecting two White Sox starters to be better over the rest of 2012, two to be worse, and one to be about the same. I’m a little more confident that Peavy and Sale will fall off than I am that Danks and Floyd will bounce back, because injuries could strike any of them down, but on the whole I think it’s fair to expect the White Sox rotation to continue to be a strength (even if how the individual members perform changes). I didn’t see the Sox challenging Detroit before the season began, but they’ve banked a 6 game lead on the Tigers now, and while there’s a lot of baseball left, the White Sox should be considered a legitimate contender.