I apologize for continuing on this Westbrook theme, but I found this article yesterday, and it piqued my interest even further. It goes a bit further than I have, examining what type of balls in play pitchers give up. The Hardball Times compiled the data and showed the outcomes (eg strikeouts, walks, groundball, etc) by percentage. It turns out that Jake gave up the greatest proportion of ground balls in the majors, 49%. More importantly, Westbrook also gave up a below-average percentage of line drives, 11%. Why is that important? HT figured the percentage of the time certain outcomes turned into outs, and line drives were caught only 26% of the time. So obviously if you're a pitcher, giving up a lot of line drives isn't a good idea.
So what's the best type of out, then? Obviously #1 is a strikeout; you will almost always record an out if this happens (the exceptions being a strikeout combined with a wild pitch or passed ball). Infield flies are next at 97%. After that it gets a bit tricky. Outfield flies (75%) become outs more often than ground balls (72%), but ground balls never become home runs; outfield flies leave the park 12% of the time.
Where am I going with this? It's very possible, if you're an extreme ground ball pitcher, to be successful with a lower than average strikeout rate. There are two big caveats, though. Number one, the pitcher has to keep his walks down. Number two, he has to have a good infield defense behind him. Obviously the best outcome would be for Jake to raise his strikeout rate to 5.5-5.8, but if his ground ball percentage sticks around 50%, it's very possible that he can be effective while posting substandard strikeout ratios. By effective I mean a 4.00-4.25 ERA, not a 3.38 ERA. That's a good middle-of-the-rotation pitcher.
Brandon Webb, who makes a nice Westbrook comp, saw his ERA increase because his walk percentage ballooned to 14%. I'd take Webb over Westbrook because of his ability to combine his sinker with a healthy strikeout rate, but his stat line serves as a reminder of what can happen if you start walking batters without compensating with strikeouts.
I'll throw out some percentages for other Indians starters tomorrow.
By the way, check out Dave Haller's excellent article on Barry Larkin (and to a certain extent) Omar Vizquel.