Durham Bulls Starting Pitcher — Saturday, 8 May

click chart for larger image

Most baseball statistics are static. By that I mean when you look at them you don’t know if the player is getting better or getting worse. So I thought I’d try to draw a picture of changes over time for our starting pitchers. I’d appreciate some readers’ comments. Is a chart like this useful? I’ll keep it up through at least one rotation and then revisit. Seems to help me get my head into the day’s game.

Carlos Hernandez has had five starts this year. He’s pitched 29 innings and has a 2-0 record. He is the only left handed pitcher on the Bulls roster.

The chart plots his FIP and ERA as they changed over those five games.

FIP (Fielding Independent Pitching) is a number built around what a pitcher can control: home runs given up, walks, hit batters, strikeouts and innings pitched. Hernandez has given up 3 homers, walked 12, hit 2, and struck out 19. What’s worrisome is that the current trend is upwards.

ERA is really affected by small sample size and the vagaries of the team behind the pitcher, meaning the quirks of “earned” vs. “unearned” rulings. Over time, these two curves should start getting closer together. But that growing FIP curve is not a good for the future. The dropping ERA is tricky to evaluate. We'll have to see about that after a few more innings.

What does this say about Hernandez? Well, these aren’t particularly good numbers. And he’s averaging less than 5 innings per start. Hernandez ended up in 2009 with an ERA of 3.29 over 112 innings, so realistically we shouldn’t expect too much more than what we’ve seen so far. If the Bulls keep up their run production, that should be enough in most games. Still, it would be nice if he could go longer in the games.