- FanGraphs Baseball - http://www.fangraphs.com/blogs -

The Nationals Do Not Give Up Home Runs

Last night, the Tampa Bay Rays connected for four home runs against Ervin Santana. It was the fifth time this year that a pitcher has allowed 4+ home runs in a single outing – the other notable hurlers to get bombed are Clay Buchholz (5 vs NYY), Josh Beckett (5 vs DET), Tommy Hunter (4 vs TOR), and Yovanni Gallardo (4 vs STL). Even as we head towards the third straight Year of the Pitcher, there are still nights where quality pitchers just don’t locate very well and pay the price for it.

That’s what makes what the Washington Nationals are currently doing so amazing. You’ve probably noticed that their pitching has been very good and has propelled them to a 13-4 record, the best mark in the National League. What you may not have heard is that the Nationals have a chance of establishing a new standard for home run prevention in a given month.

The Nationals have faced 644 opposing batters this year, and exactly three of them have hit the ball over the fence. On April 9th, Kirk Nieuwenhuis took Edwin Jackson deep in the fourth inning. Then, on April 15th, Ross Detwiler gave up a first ining homer to Ryan Ludwick. They didn’t give up another long ball until Logan Morrison took Brad Lidge deep in the ninth inning on April 21st, and they haven’t given up one since.

How amazing is this early run of HR prevention? The Pirates have allowed the second fewest homers so far this year, and they’ve surrendered 10 home runs while facing 69 fewer batters. The next best home run rate in the game belongs to to the Texas Rangers, who are surrendering one home run for every 60 batters they face. The Nationals have allowed one home run for every 215 batters that have stepped in against them. The Nationals home run prevention rate is 3.6 times better than the next best rate this year.

I’m sure other teams in baseball history have had a month like this before – after all, the 1904 Pirates gave up four home runs for the entire season, so they obviously had a bunch of individual months where they allowed fewer than three home runs. The game was different then, however, and comparing what the Nationals are doing now to what the deadball era isn’t overly instructive.

So, I asked the Dark Overlord to query out the single best months in terms of home run prevention by a team since 1974. We’re throwing out strike/lockout shortened months, so the June of 1981, August of 1994, and April of 1995 are out. We’re also going tossing out the months where the season began in mid-April because of the low number of games played – for instance, the 1976 Tigers only allowed two home runs that month, but they only played 13 games and faced just 494 batters.

That leaves us with the current top three HR prevention months by a team since 1974, sorted by HR/9:

Houston Astros, May of 1981: 29 G, 1,161 TBF, 5 HR allowed, 0.16 HR/9

Houston Astros, August of 1980: 30 G, 1,205 TBF, 6 HR allowed, 0.19 HR/9

Los Angeles Dodgers, April of 1985: 21 G, 755 TBF, 4 HR allowed, 0.19 HR/9

The Nationals current run would rate right in between those two Astros seasons, as they currently stand at 0.17 HR/9. It probably shouldn’t be a big surprise that Houston comes out on top or is represented multiple times, as the Astrodome was a ridiculously pitcher friendly park during its heyday. And, of course, home runs weren’t as common back in the 1980s as they are now. In fact, for context, here are the league average HR/9 rates for the months listed above:

May, 1981: 0.63
August, 1980: 0.73
April, 1985: 0.75
April, 2012: 0.95

Adjusting for era, what the Nationals are doing in this day and age is perhaps even more impressive than what the Astros did back in 1981. I say perhaps because, while their HR rate adjusted for league average is more impressive, they’re also doing it in a significantly smaller sample size. If they can get through their final five games of April (the next two of which are in Petco, followed by three in Dodger Stadium) without giving up any home runs, they’d end the month with around 840 batters faced, and it’s obviously easier to sustain this kind of insane performance over a shorter period of time.

So, we can’t say that this definitively the best month of home run prevention that any team has had in the modern era, but it is at least in the discussion.