Ivan Nova needs to keep fastball down to keep ball in park

Ivan Nova said before the start of spring training he feels he doesn't have anything to prove, and that he's confident he'll earn a spot in the Yankees' starting rotation this year.

The Yankees' organization must be pleased by Nova's attitude, especially after viewing his struggles in 2012 -- 12-8, 5.02 ERA -- as more of an “above the shoulders” issue than a talent problem, as Newsday's Erik Boland reported earlier this spring.

Perhaps, however, both parties should be looking to the area above the outfield wall as the true source of Nova's troubles. And perhaps that watch should start...oh, about now.

By many measures, Nova actually improved his major league performance last season. His 170.1 innings were the most of his young career. His 8.1 strikeouts per nine innings was his highest rate ever, far outpacing the 5.3 K/9 rate he posted during a generally successful 2011 season. His 3.0 walks per nine innings was a career low.

Then there's the matter of home runs.

After giving up 13 home runs in 165.1 innings in 2011, Nova allowed 28 last season, more than doubling his home runs per nine inning rate from 0.71 to 1.48.

Only five other hurlers with at least 150 innings pitched posted a higher rate in 2012: Jeremy Guthrie, Bruce Chen, Derek Holland, Phil Hughes and Ervin Santana. Four out of the five posted ERAs of 4.67 or higher. Only Hughes escaped with a respectable 4.23 ERA.

And the Yankees could have seen Nova's decline coming.

Before his standout 2011 season, during which Nova groundballed his way to a 16-4 record and 3.70 ERA, he allowed just a single home run in 20 spring innings, posting a 2.5 ground out to air out ratio. But in February and March of 2012, Nova allowed five home runs in 22.1 innings of spring training, and his GO/AO dipped to 0.92.

He was being more careless in the strike zone, and heat maps on fangraphs.com show that tendency carrying over into the regular season when Nova's ground ball percentage dipped from 52.7 in 2011 to 45.2 in 2012. He also wasn't quite as lucky. Each of Nova's 13 home runs in 2011 were solo shots. In 2012, 19 were solo home runs, six were two-run homers, one was a three-run homer, and two were grand slams.

There's reason to believe Nova's home run issues were an aberration, though. During parts of six seasons in the minors Nova only once had a HR/9 over 1.0, and that was during his brief demotion to Triple-A during the 2011 season, when he posted a 1.7 HR/9 in three starts. His minor league average was just 0.6.

So while it's great that Nova's confidence level is up, it might be a better gauge of his abilities to make sure his fastball isn't.