Josh Collmenter had an excellent Rookie season. His 3.38 ERA , (117 ERA+) were very good. His WHIP was an excellent 1.069. He did a great job at keeping runners off base.

The underlying peripherals are very interesting, and while not unique, presented a somewhat rare statistical profile last year. Specifically, his walks per 9, and his BABIP were extremely low. These two numbers were the underpinning of his success, as his HR/9 and K/9 were a little worse than league average.

How do the numbers in his first MLB season compare to his minor league career ?

So how rare is it for a pitcher to have this kind of BABIP and walk combo ? Pretty rare.

In 2011, there were only two pitchers to throw at least 140 IP and have a BABIP under .270 and a BB/9 under 1.70, Collmenter and Josh Tomlin.

Note: I really encourage people to follow the links and study the tables.

http://bbref.com/pi/shareit/CcdIY

In the last 20 years there have been 18 such season, (3 by Greg Maddux). Tomlin and Collmenter are the first guys to do it since 2005

http://bbref.com/pi/shareit/RTQQB

What about going forward ? How likely is it that Collmenter can continue to have a BABIP under .270 ? It's been said that he is "tough to square up". Thats certainly true to some degree. He is a fly ball pitcher, and the vast majority of the flyballs he allows were very catchable balls last years. His minor league BABIP of .293, while much higher than last years, is still better than the average minor league BABIP, which is usually higher than it is in MLB. (Better fielders in MLB of cours e).

How many pitchers in the last 20 years have thrown at least 400 IP in the majors and had a sub .270 BABIP ?

TEN PITCHERS IN 20 YEARS HAVE BEEN ABLE TO SUSTAIN A SUB .270 BABIP FOR ANY REASONABLE PERIOD OF TIME

http://bbref.com/pi/shareit/B0SMT

As a side note, the guy on that list that I most liken Collmenter to is Chris Young, formerly of San Diego. He had several years where he was really effective when he could actually post up and pitch. He was tough to pick up like Josh, and also an extreme flyball pitcher. But back injuries killed his career.

So what about the walk rate ?

EIGHT PITCHERS IN 20 YEARS HAVE BEEN ABLE TO SUSTAIN A BB/9 RATE UNDER 1.70 FOR ANY REASONABLE PERIOD OF TIME

http://bbref.com/pi/shareit/QPHPc

And finally, what about the combination of low BABIP and low walks ? Well, you have to bring the BABIP up to about .285 to get anyone on the list at all.

BABIP LESS than .285, BB/9 Less than 1.7

http://bbref.com/pi/shareit/Opkrv

CONCLUSION:

Well, I really don't have a hard and fast conclusion. Obviously I am prone to think that some regression to Collmenter's BABIP and Walk Rate are higly likely, or I wouldn't be posting this. The added baserunners would certainly drive up his runs allowed. On the other hand, he may continue to develop his curveball and increase his K Rate, allowing fewer balls in play, somewhat offsetting an expected regression to his BABIP. But if his BABIP goes up to say .290, which would still be better than league avg, and his BB/9 goes to 2.5, then you would be looking at about 27 more baserunners in the same 154 IP

That would mean an increase in WHIP to about 1.25. And you know what ? Thats still pretty good. As long as the HR rate doesn't spike, he can be a decent run preventer with that kind of profile.

I think some of the early projections for an ERA around league average are pretty reasonable. And who knows, maybe he can continue to throw strikes as effectively as he did last year while adding wrinkles to his arsenal. If he can do that, keeping an ERA south of 3.50 is not out of the question.

Good luck Josh. Keep throwing strikes no matter what. And keep working on that curveball.