Chapman to Start?

The newest out of Reds camp — other than the completely unsurprising fact that noted veteran-lover Dusty Baker won’t declare Devin Mesoraco his number one catcher yet — is that the team might try Aroldis Chapman in the rotation. From a team value standpoint, it makes all the sense in the world. From a fantasy standpoint, however, his prognosis is mixed.

Obviously the Reds wanted more out of their $30 million dollar Cuban. Since signing with them, he’s given them 63 innings in two years. Even with premier velocity readings and a wicked slider, that’s been worth (at most) a win and half to his team. Add in the fact that Bronson Arroyo and Mike Leake provide an uninspiring duo at the back end of the rotation, and the fact that 39% of starting pitchers that pitched last year will hit the DL this year (meaning the team will need a sixth and seventh starter), and it’s almost a lock of a move for the team. They have to at least try him in the rotation — especially now that Sean Marshall and Ryan Madson have the pen on lock for the short term.

How will he do?

Tom Tango at the book blog has a ‘rule of 17.’ If a starter moves to the pen, his strikeout percentage goes up by 17%, his batting average on balls in play goes down by 17%, and his home runs per plate appearance goes down by 17%. Chapman had an elite strikeout percentage (34.3%), enjoyed a .242 BABIP, and gave up just two home runs in his 50 innings last season. He can survive a hit in those categories.

The problem is that Tango also found that walk rate is flat in the move from the rotation to the pen. And that’s too bad for Chapman.

Over the last two years, with a minimum of 60 innings pitched total, Chapman’s 17.8% walk rate is the worst in baseball. By a percentage point and a half over Tim Collins. If his strikeout rate falls and his walk rate stays the same, he won’t be a very compelling fantasy play.

Look back at the laggards in walk rate over the past two years, on the other hand, and you’ll see that it takes a while to find a starter. Andrew Miller (13.9%) and Kyle Drabek (13.8%) made the list as the first starters, but even they didn’t last a year. Comb through the ranks and you’ll find Edinson Volquez and his 13.1% as the first pitcher with over 170 innings in the two years combined. Jonathan Sanchez (12.9%) was the first to manage over 250 innings.

Obviously, this doesn’t mean that Chapman will automatically start walking about 13% of his batters once he moves to the starting rotation — plenty of pitchers flamed out as starters because of their high walk rates and the leaderboard would suffer from survivor bias. But it’s a reminder that Chapman won’t make it as a starter with a 17% walk rate.

Good thing he managed a 12.7% walk rate in the minor leagues.

If you reduce Chapman’s strikeout rate by 17%, he’d have a 29% strikeout rate — that would have been first among qualified starters last year. If he can manage a 13% walk rate with that (and retain his excellent ground ball rate), he’d be better than Jonathan Sanchez, who had a strikeout rate around 24% and a below-average ground-ball rate along with his near-13% walk rate over the past two years. He’d also be better than Gio Gonzalez, who only struck out 22.8% to go with his 10.5% walk rate and ~48% ground-ball rate.

Those might not be the comps the Reds were looking at when they signed Chapman to his big deal, but they are productive pitchers. If he fell between the two, he’d even be a fantasy monster relative to his price.

But we can’t say with certainty that he can even cut his walk rate to 15% in the Major Leagues. And until he shows he can, history says he won’t make it as a starter. Since 1980, only three starters have managed to qualify for the ERA title with a walk rate over 15%. One of em was some guy named Randy Johnson, though. Did it twice even.