Sunday was a day unlike any other in baseball history. Per Elias Sports Bureau, consider this tidbit: Ten starters Sunday went at least seven innings allowing three or fewer hits, the largest number on a single day all time.
Apparently it wasn't a statistical anomaly.
Digging deeper, after the discussion came up between Eric Karabell and me on a recent Fantasy Focus Baseball podcast, it turns out that there is something to the day of the week affecting player performance. Sunday, at least in recent history, has been a lower-scoring, more pitching-oriented day.
Using data since 2011's Opening Day and including the 2014 season to date, the following chart calculates leaguewide statistics by the day of the week, the caveat being that the sample sizes for Monday and Thursday are noticeably lower than for the other five days because those are the most common off days on the calendar. (The percentage of the league's total games played by day goes like this: Saturday 16.2 percent, Sunday 16.0, Friday 15.7, Wednesday 15.4, Tuesday 15.0, Monday 11.5, Thursday 10.3.)
Although the differences are indeed minimal -- those Sunday stats amount to an average of about two fewer hits in all games played compared with Mondays, Tuesdays, Thursdays or Fridays -- they do represent evidence that odds, however small, are indeed better for pitchers on certain days. It's no coincidence that the lesser offensive days appear to be Sundays, Wednesdays and Thursdays, in that order, as these tend to be "getaway" days, with a larger number of day games immediately after night games.
Theorizing here, the obvious reason for this would be teams' interest in resting veterans, especially older ones, for day games after night games. Conversely, as Friday -- the most productive hitting day of the week -- is typically populated by series-opening night games (many of those after a scheduled day off), star players are considerably less likely to take a seat.
But let's not just assume that to be true. Running the numbers accounting for the top 25 percent of qualified hitters -- which is a group of 111 players with at least a .333 weighted on-base average (wOBA) -- the following chart backs that up. In this case, let's add "Play%" to represent the percentage of all teams' available lineup spots on the given day occupied by this sample of players from 2011 to '14.
It's that Play% column that's most interesting: Star players indeed sat most often on Sunday, accounting for 1.1 percent fewer starts than on any other day of the week, and the ones who did play produced lesser numbers than on the other days. Again, the next-most frequent "sit" day was Wednesday.
Oddly, during this past Sunday's standout pitching day, David Ortiz was the only significant fantasy stud to sit, as he enjoyed only his second day off in 2014 (his only other occurred on a Friday, April 18). Still, he sat out five Sundays in total in 2013, although two of those were while he was on the DL early in the year. It shows that this is hardly a widespread thing; it is merely an estimate-your-odds angle.
Using 2013 Player Rater data to test this, consider that the top eight finishers among hitters totaled 83 non-starts (team games in which they were absent from the starting lineup). This group amassed 20 of those 83, or 24 percent, of those on Sundays alone. That's not to say Mike Trout, Miguel Cabrera and Paul Goldschmidt are probably going to sit most Sundays; it's saying that their odds of sitting a Sunday are greater than on other days, and that, if you have opposing pitchers facing their teams or are their owners and are in tight head-to-head matchups, it means you should be especially mindful of checking those early lineups (remember that, typically, all but one game on a given Sunday begins during the day).
From a pitching standpoint, it means Sunday -- "rally day" in head-to-head leagues, in which owners playing from behind often load up on streaming starters -- is an advantageous day in those formats with daily transactions, as our standard leagues allow. In weekly leagues, though, it also props up the value of two-start pitchers. Those locking in a two-start pitcher with a second turn on Sunday, as a majority of two-start pitchers have, know their odds are slightly greater in that second start.
Finally, and to provide evidence of that, look at the chart to the right, which breaks down starting- and relief-pitching statistics by day of the week.
Quality-start percentage is highest on Sunday, as is length of outing. In other words, pitchers who draw the "getaway day" assignments have an inherent advantage because they're slightly more likely to face "B" lineups on those days.
But here's what's most puzzling: Closers don't appear to gain any advantage at all, with the volume of saves being greatest on those Wednesdays (but not Sunday, when they are actually worst by four-thousandths of a percentage point). You might think lower scoring would result in greater saves production, but that's not so. Frankly, looking at those saves numbers, it seems that's a mere statistical anomaly.