Now, it's worth noting that Cahill's ERA still ranks third in the league. And that one of the guys with a lower ERA (Felix Hernandez) is just 10-10, and the other (Clay Buchholz) has essentially the same record (15-5) as Cahill's. It's also worth noting that the Cy Young race is wide open. With an 18-5 record, CC Sabathia's obviously the No. 1 candidate, but his ERA is just eighth best in the league, and if he drops a few more spots on that list, some voters will go looking for a candidate who's been a little better at preventing runs.
Cahill does have a case, based on his ERA and his record, the two legs upon which most Cy Young candidacies stand. There is a third leg, though: strikeouts. And that's where Cahill falls well short of the other candidates.
How does Cahill have such a low ERA despite so few strikeouts?
You probably know. Cahill has induced a huge number of ground balls -- in the American League, only Justin Masterson has coaxed more of them -- and he's also been extraordinarily lucky, with a .224 batting average on balls in play (BABiP) that's the lowest in the league by a whopping 33 points.
Should Cahill's BABiP have any bearing on his Cy Young candidacy? I lean toward yes, but today I'm not willing to engage in some lengthy philosophical discussion. Rather, I'm curious about what BABiP says about the future of Oakland's impressive young rotation.
Look, regardless of what you think about Cahill's season, BABiP tells us -- in this case, with great conviction -- that his ERA won't be nearly as low this season. In the high minors -- and he wasn't there for long, at all -- Cahill struck out a lot of guys, but he also walked a lot of guys. He seems to have made the eminently reasonable decision to throw more strikes and get loads of ground balls, and it's working brilliantly for him. But if you want to be a sinker-baller and a perennial Cy Young candidate, you still have to rack up some strikeouts. From 2006 through '09, Brandon Webb averaged seven strikeouts per nine innings; Cahill's at five per nine innings this season.
Looking ahead, Cahill's demonstrated ceiling is goodness rather than greatness. Of course, he's only 22 and he's still got time to demonstrate something else. With that in mind, let's look at all the young Athletics starters this season: Age, ERA, and BABiP ...
Trevor Cahill: 22/2.82/.224
Gio Gonzalez: 24/3.23/.278
Dallas Braden: 27/3.28/.273
Brett Anderson: 22/3.32/.315
Vin Mazzaro: 23/3.61/.284
We would expect Oakland's pitchers to have relatively low BABiPs, because Oakland's fielders have the highest Defensive Efficiency Rating in the major leagues this season. Braden's and Gonzalez's numbers are a little low, but not so low that anybody should worry about them.
Obviously, BABiP is just one metric. And while it's somewhat tyrannical, it's not the only metric. We could look at ground-ball rates and strikeout-to-walk ratios, too (among other things). And Mazzaro in particular probably doesn't have the skills to consistently support a sub-4.00 ERA. But with the exception of Cahill, BABiP doesn't suggest significant regressions next season for any of the A's young starters.