All statistics in the first month or two of the baseball season, and sometimes even longer, carry with them the same qualifier: sample size. A .414 BABIP? Likely to diminish as the season continues. A .952 LOB% for pitchers in April? Don’t expect it last. Small sample size. It’s the go-to phrase for statistical anomalies.
Most fans that would care about these numbers in the first place can sing the sample size song. But at what point do we start taking the numbers seriously? At what point is the sample size no longer considered small?
In 2007, baseball thinker Russell Carleton tackled this question in a piece that was equal parts brilliant, nerdy, and confusing. (If your kind of leisurely read typically includes phrases like “Because a correlation of .70 means an R-squared of 49 percent,” then this article is for you.)
Carleton concludes that certain statistics take longer than others to be considered an honest indicator of performance. For instance, it takes about 500 plates appearances for OBP to become reliable, whereas fly ball rate is reliable at 250 PA.
At this point in the season, most everyday starters have somewhere in the neighborhood of 150 PA, give or take a few. From this sample size, Carleton claims that the following statistics are reliable performance indicators (check links for statistic definitions): swing percentage, contact rate, K rate, line drive rate, and pitches per plate appearance. At the 150 PA mark, those five statistics, as Carleton points out, tell us something about a player.
Enter Jay Bruce.
The 26-year-old right fielder has struggled mightily, by his standards at least, in the batter’s box this season. He is regularly slotted at the No. 5 spot in the lineup, behind on-base machine Joey Votto and Brandon Phillips, so Bruce theoretically should have more pitches to hit than most batters. But so far, his numbers are far from the kind we have come to expect from the two-time All Star. Through Tuesday, Bruce has a career-worst BB% (6.5 percent) and OPS (.709, nearly 60 points lower than his rookie season). He is also on pace for about 198 strikeouts, a number that could make even a donkey blush.
These numbers are clearly not promising at the moment, but are we at a point where they are a legitimate concern? I took to Carleton’s chart to see how Bruce has performed based on the aforementioned statistics that are the most reliable at this point in the season. (I ignored P/PA because I don’t see it as particularly significant and because, so far, it was falling right in line with his career good average.)
Here’s the bad news.
Bruce is swinging at more pitches than he ever has before. His swing percentage is at 52.5 percent, nearly four percent higher than his career average at 48.7 percent. That is a significant increase, but it wouldn’t be a problem if he were making contact with those extra swings. He isn’t. His contact percentage, which is typically lower than league average to begin with, has slipped to 72.0 percent.
Quick pop quiz: Swinging More + Making Less Contact =_____.
If you guessed more strikeouts, you would be correct.
Bruce’s strikeout rate is an astronomical 30.6 percent, second highest among players that have reached the 150 plate appearance mark. (Though I should note that Dan Uggla and Chris Carter, whose K Rates are higher than Bruce’s, are only one and two at-bats away from the mark, respectively.) But for fear of Bruce calling me an idiot, I went for a Bradley Cooper-style garbage-bag run in search of a silver lining and found Bruce’s line drive percentage.
Bruce’s LD% has increased to an impressive 29.9 percent, and anyone who has read this space this season should know about the importance of a high LD%. Bruce’s number is actually tied with Votto for second-best in the league. This means that when he does hit the ball, he is making mostly solid contact and driving the ball rather than swinging for the fences. (Though his infield fly ball rate is up almost 5 points this season to 11.1 percent. That’s not so good. So…let’s focus on his LD% instead!)
The line drive rate is promising, and perhaps some of those infield fly balls will catch the sweet spot. But none of that will matter if Bruce can’t get the bat on the ball. The problems behind his low contact and high swing rates need to be solved soon if the Reds are going to compete for a pennant. Sample size is no longer an excuse.