ESPN analyst and former major league player wrote a blog entry called Enjoy it for what it's worth. Sky Kalkman at "Beyond the Boxscore" wrote a response called Defending Harold Reynolds. Reynolds criticizes some of the "newer" stats like OPS:
"Not all statistics work. Some do, some don't. And one of the stats that has become real popular is OPS. On-base plus slugging. All of a sudden, it's this stat that defines whether a guy is a good ball player or not. And the fact of the matter is, if you're a power hitter then the situation will dictate what a pitcher does with you - either walk you or pitch you real careful. So more than likely you're going to end up on base and therefore your on-base percentage goes up. This in my mind has become the stat the everyone thinks is the be all and end all. It is not. If you have a ball club that's a great offensive team then that changes everything. But if you have a guy like Adrian Gonzalez, for example, his OPS is going to be high - he's got a lot of home runs and walks a lot...because you're not going to pitch to him. Power guys like Giambi and Dunn have always had high OPS because no one wants to pitch to them. But it takes two hits to score them from first."
Reynolds began by saying that context and situation matters and it probably does. But this raises the question of how much? Some of my past research touches on these issues and I will discuss that below. But first, even if you don't like OPS, or OBP + SLG, it is still better than the traditional stats (for example, he mentions that Ichiro Suzuki gets 200+ hits every year). The 1998 STATS, INC. Baseball Scoreboard book had a nice little study that showed that the team with the highest OPS in a game has a winning percentage of .852 while it was .804 for batting average (they looked at several other stats and OPS had the highest winning percentage).
But let's look at some of what Reynolds said specifically. He seems to be saying that when a slugger walks on a weak hitting team, it is not so valuable. But I had done some analysis on this. It was called The Value of OBP and SLG by Lineup Position for High-Scoring and Low-Scoring Teams. If you go to this link, you will see that the marginal run value for the cleanup hitter's OBP is actually higher on the low scoring team.
Now how much might context matter or change our evaluation of hitters if we are using OBP and SLG? My analysis on this is called Evaluating Hitters Based on Their Lineup Slot. The most anyone was adjusted was a +6.2 runs per season, for Luis Castillo. So if I took into account that he was a leadoff hitter instead of a generic hitter, his value to his team would be about 6 more runs a year. This seems pretty small. So context does not change our valuation much.
Then there is the issue of situational hitting. My analysis on this is called The Problem With “Total Clutch” Hitting Statistics. What I found was that OPS was highly correlated with how much impact a hitter had on winning and losing depending upon the situation. The stat I used was Ed Oswalt’s measure “player’s win value” (or PWV). It makes a HR in a close and late game more valuable than one in a blowout. It calculates how much each hitter's result changed his team's chances of winning. The correlation between PWV/PA and OPS was .948 (a perfect correlation is 1.00). The relationship was even stronger when I broke down OPS into its separate components of OBP and SLG. So the bottom line is that we really don't need to know the situations a player faced to evaluate him. His regular stats tell us that.