Grant Balfour in Baltimore

Grant Balfour has never called a hitter-friendly stadium home. He’s about to, since he signed a two-year deal to ostensibly be the closer in Baltimore. Will it matter?

It might. Only 16 relievers had a lower ground-ball rate and threw 100 innings over the past two years. Even calling Oakland home, he gave up more than a homer per nine innings in 2013. He gave up slightly more homers per inning on the road this year, too. Here’s a fly ball pitcher, straight out of Oakland (92 park factor for home runs) and Tampa (96), heading to Baltimore (110).

The ‘reason’ for the different park factors between the parks is not immediately clear. Camden Yards and o.Co Coliseum have virtually identical dimensions, with Camden’s 12-foot shorter right field line the biggest difference. As a right-hander with 93+ mph gas, that part of the park is not such a big deal. But the weather! The data is a bit old, but Mike Fast showed that Oakland was the coldest park in the league, on average, and Baltimore was the fourth-hottest. Balls fly further in warmer weather, and on average, balls might fly six feet further in Baltimore.

So let’s say he’s a candidate for the worst home run rate of his career. Since his rookie year, that was his 1.16 HR/9 that he put up in 2011. If he strikes guys out and doesn’t walk them, maybe not a big deal, right? With the 29th-best strikeout rate among qualified relievers and a walk rate just a bit worse than average, maybe he’s okay either way.

Well, what about that dip in swinging strikes and strikeout rate in 2011 and 2012? He did gain a half tick on his fastball in 2013, and maybe that had to do with the jump in swinging strike rates on the pitch (from 7% to 9%). But his slider and curve got better, too. Well, they had less movement in 2013, but they had a bit more gas, and maybe a tick more gas in each department was all he needed to make every part work together.

It could be as simple as health. In 2011, Balfour had an oblique injury that felled him for a few weeks. It may have hung around. In early 2013, he had knee surgery and said it bothered him late in 2012. And yet, his velocity charts don’t fit this narrative:

In fact, for a 36-year-old, that’s a remarkably steady velocity chart. He’s not throwing 95 like he used to, but 93+ will work.

It’s not a sexy story, and neither is they signing. You can’t pinpoint one reason Balfour was better in 2013 than he had been before, and though he can expect his fly balls to fly a little further, he’s been effective with high-ish home run rates before. As long as he can command the ball — a return to a league-average first strike rate would go a long way towards reducing his walk rate — he can avoid the baserunners that make the occasional long ball a more cumbersome problem. And though Tommy Hunter is better with 95 mph gas than he was as a starter, only his fastball and cutter get league-average whiffs and his vaunted curveball suffers against lefties.

Grant Balfour in Baltimore: maybe not as good as Grant Balfour in Oakland, but probably still a decent bet for saves. As long as he brought his rage with him.