In recent years – really going back to the start of the current decade – OPS (On-Base % + Slugging %) has become a mainstream stat in Major League Baseball. Many local and national broadcasts display the batter’s OPS during their first at bat, or in some cases, every at bat. The starting point for OPS is the idea that hitters’ value is tied to their ability to reach base and ability to hit for power. OPS takes the two rate stats – OBP and SLG – that account for on base and power ability, respectively, and combine them as a means of quantifying a hitter’s total value. The flaw in OPS is rather obvious. It assumes that on base ability and power are equally valuable which is not necessarily true, but it’s an easy statistic to understand and provides a snapshot of a hitter’s value.
There is, however, a second and perhaps more pressing issue with OPS. A hitter’s value is relative to that of his competition. A player with a .700 OPS might not seem that great, but if the league average is .650 than .700 is a pretty good mark. Likewise, a .900 OPS might not seem great but if the player plays most of his games at a hitter-friendly park – Coors Field, for example – and benefits greatly from that environment, then maybe that player didn’t hit as well as it might initially appear. Performance is relative to context.
OPS+ takes that context into consideration. First, it compares each player’s OPS to the league average OPS. It also adjusts for Park Factors. That number is then rescaled with an OPS+ of 100 as the mean. Any number higher than 100 is better than league average and below 100 is below league average. This is done on a seasonal basis.
For now, we will ignore park values because in terms of runs scored, Horn and Sheff did not play all that differently from one another in 2017. Also, there was not a team that played a significant majority of its games on one field or the other. For those reasons, it is safe to assume that fields would have little impact on our ability to compare hitters for the 2017 Mid Atlantic season. For our purposes, OPS+ will be a simple formula:
(OPS/League OPS)*100
The results for the 2017 season can be found below (Min. 50 PA’s). Full results can be found here.
The first thing that jumps out at me is that OPS+ is far easier to digest than OPS when evaluating the 2017 Mid Atlantic hitters. The reason for that is that the average OPS of an MAW player in 2017 far higher than that of a Major League Baseball player. It is tempting to look at – for example – Dan Isenberg’s 1.027 OPS and conclude he had a monster season at the plate. That would be a monster season in the 2017 MLB environment but not so much in the 2017 MAW environment. In fact, Dan’s OPS of 1.027 works out to a 100 OPS+ which means he was exactly a league average hitter. A relative statistic like OPS+ cuts through the noise of the base stat by making it relative to league average performance.
That’s a positive. Another positive is that the results pass the smell test. The players with above league average performance do not seem out of place at all.
Where OPS+ fails here – in addition to the general problem of weighting OBP and SLG equally – is the rather large variance in pitching quality this past season in the Mid Atlantic. There were some very, very talented pitchers, some average pitchers, and some poor pitchers. The usage of these pitchers (unlike in MLB) wasn’t random either. Lesser quality pitchers tended to be used against teams that had some combination of weak hitting and subpar pitching. In other words, some teams faced other teams’ 3rd, 4th, or even 5th pitchers on a regular basis while other teams regularly faced team’s 1st or 2nd pitchers. It is rather clear from the results that this had an impact. To adjust for that, we could assign a factor to each MAW pitcher based on their 2017 performance (i.e. run prevention) and weigh a batter’s performance based on the quality of pitching he faced. For example, a hit off of the best MAW pitcher would earn that hitter extra OPS+ points while hits off of the worst pitcher would result in less credit given to the hitter.
But I am getting ahead of myself.
Looking at OPS+ as it is, it is a semi-valuable statistic for the 2017 MAW season. It provides a quick and dirty look to how a hitter performed against the competition he faced relative to other hitters that passed through. There is some value in that, although as noted, not every hitter faced the same level of pitching which does significantly impact the results. At a later point, we will attempt to adjust for that discrepancy. For now, OPS+ is a useful tool for evaluating MAW hitters in 2017 as long as we keep that pitcher variance in the back of you mind when using OPS+ for evaluation purposes.