2008 vs. 2009
* All stats courtesy of Baseball-Reference
The most obvious differences between this year and last year aside from ERA and WHIP come from vast improvements in strikeouts per nine innings (SO/9) and hits allowed per nine innings (H/9). Although the Tigers have slightly reduced their BB/9, their significant reduction in WHIP can be largely attributed to giving up fewer hits. The Tigers are giving up nearly one fewer hit per nine innings which is a big enough improvement to move them from 10th in the AL last season to 3rd this season. Based on the total number of hits and runs scored in the American League in 2008, one hit is roughly the equivalent of a ½ run which is almost exactly the difference between Detroit’s 2008 and 2009 ERAs. Clearly, the Tigers are pitching much better this season because they’re giving up fewer hits.
How/why are they giving up fewer hits? The Tigers are striking out 1.2 more batters per game. More strikeouts mean fewer balls in-play (Tigers “in-play%” has dropped from 70% to 68% from last season). Fewer balls in-play mean fewer hits. Fewer hits mean fewer runs. Fewer runs mean better pitching. Better pitching means, well, you get the idea!
I was curious to see exactly how/why the Tigers are striking out more batters this year so I decided to take a look at strike % and first pitch strike % to see if a significant increase in either number may be leading to a higher SO/9. Surprisingly, the numbers from 2008 are nearly identical to what they’re doing this year. The Tigers had a strike % of 61% last year and are at 62% this year. Their first pitch strike % for both this year and last is right at 58%. If the Tigers are throwing nearly the same number of strikes and the same number of first pitch strikes, then how are they racking up 1.2 more strikeouts per game than last year? My only guess is that they’re eliciting a higher percentage of strikes via the “swing and miss” and/or “looking” variety. In fact, the Tigers are causing hitters to "swing and miss" more often this year. They lead the league in total percentage of strikes that are "swings and misses." Equally important to consider, though, is that "balls put in play" count as "strikes." If a team throws the same number of strikes but reduces the number of "put in play" strikes and increases the number of "swing and miss" strikes, then the result is more strikeouts which is exactly how the Tigers have done it. To summarize, the Tigers are striking out more hitters this year not necessarily because they're throwing more strikes but because they're throwing more of the right kind of strikes. Translation: more gas.
Now let’s put some faces behind the numbers. Last year, the Tigers had two starting pitchers who were among the worst in the AL in H/9. Those two pitchers were Kenny Rogers and Nate Robertson. They yielded 11.0 and 11.6 H/9, respectively in 2008. The Tigers replaced Rogers and Robertson in the starting rotation with Edwin Jackson and Rick Porcello. Jackson and Porcello have given up 7.4 and 8.2 H/9, respectively. That is a significant difference. One of the main reasons Jackson and Porcello aren’t giving up nearly the number of hits that Robertson and Rogers did is because they are striking out many more hitters. Robertson and Rogers combined for 10 SO/9. Jackson and Porcello have combined for 12.8 SO/9. Jackson and Porcello are clearly upgrades over Rogers and Robertson and they come with the added bonus of being a combined 28 years younger.
The Tigers replaced to below average starting pitchers with two above average starting pitchers. Those two changes are almost solely responsible for the monumental improvement in pitching from last year to this year. While it’s encouraging to see Jackson and Porcello pitching so well, it’s important to remember that Jackson is having the best year of his career by a landslide and Porcello is only 20. If either or both struggle for an extended period of time, then the Tigers’ chances of winning the division likely evaporate.
As for the rest of the rotation, Justin Verlander is much better, Armando Galarraga is much worse, and Zach Miner is/was Zach Miner. Miner has been replaced by Dontrelle Willis but “the Big Smile” won’t last much longer in the rotation if he continues to yield more runners than a Columbian drug cartel. The Tigers have pitched very well over the first 1/5 of the season. However, winning the division is an unlikely proposition if Galarraga remains abysmal and the fifth-spot continues to produce like the Potato Famine of 1845. That’s why I think the return of Jeremy Bonderman to at least a serviceable level is absolutely crucial if the Tigers have any shot at pitching their way to the Central Division title. We've seen how big of an impact replacing two below average starters with two above average starters has had. If the Tigers can do that one more time by eventually getting Bondo back into the starting rotation, then that could be the difference between merely contending for the division and winning the division. Of course, Willis going from a below average starter to an above average starter would work, too.