April was bad. The 9-19 record made Astros fans believing that 2014 could possibly be worse than 2013, which seemed impossible before the season.
As most people know, since then things have been much better for Houston - especially the pitching staff, and even more especially, the starting pitching. The 3.92 FIP of June isn't quite the outstanding 3.35 mark of May, but it certainly isn't as bad as the 4.48 FIP that Astros pitching had in May.
The reasons for improvement are vast. Collin McHugh's appearance, Dallas Keuchel's emergence, Jarred Cosart's consistency and the reliability of Chad Qualls all have been very helpful.
But as a whole, a gigantic reason for the improvement of Houston pitchers is the fact that they are keeping the ball in the park at a historic rate. So far, Houston has allowed 65 home runs in 78 games, putting them on pace for 135 opponent homers.
135 would be the least amount of long balls Houston has ever allowed in a season while calling homer-friendly Minute Maid Park (and previously, Enron Field) their home. The prior low came in 2010 when Houston allowed 140 home runs. Since the ballpark opened in 2000, Houston has been among the five worst teams in allowing home runs in six different seasons.That includes last season's 191 home runs conceded, 106 of which came at MMP. Furthermore, from 2006-2013 the Astros have allowed 1.13 HR per nine innings - the second-worst rate over that span.
Back to this year's horrid April, where it appeared like more of the same. 30 homers were hit off Astros' pitching in 28 games and Houston was 10 games under .500. Usually home runs come more frequently as the weather gets warmer, but as it's gotten hotter, Houston has gotten better. Since the end of the season's first month, pitching coach Brent Strom has seen his staff surrender only 35 home runs in the last 51 games. In the 30 days before last night, Houston had an MLB-best 0.40 HR/9 rate. Then the Upton brothers came to town.
Now let's give credit where credit is due - the Houston starters are the main reason why the Astros look so good at preventing the long ball. The Astros' starters are giving up only 0.75 HR/9 (38 HR in 458.2 IP), while the the injury-ridden bullpen is allowing 1.05 HR/9 (27 HR in 231 IP).
More specifically, Keuchel, Cosart and McHugh have been outstanding in preventing the long ball. Keuchel's 0.43 HR/9 is the eighth-best rate among qualified inning throwers in 2014. Cosart is at 0.61 HR/9 and has allowed only one home run since May 5. McHugh's 0.55 HR/9 would 17th among pitchers in MLB if he had enough innings to qualify.
The best team at preventing home runs? Unsurprisingly, it's the St. Louis Cardinals with a pitching staff heavily filled with Luhnow products. As you would expect, there's a correlation between inducing groundballs and preventing home runs. Although, it's not always the rule with every pitcher, it makes pretty simple sense - more balls on the ground mean less balls out of the ballpark in the air.
Preventing home runs is one of many traits teams want in their pitchers, and the Astros pitchers all have things they can work on. Home runs are the quickest way to score and the biggest momentum shifters, and in 2014 is a big reason why the Astros are not only winning, but are at least competitive in so many more games.
All statistics courtesy of Fangraphs.