The value of OBP is more significant than the value of SLG, simply because of the difference in the numbers. A perfect OBP is 1.000, while a perfect SLG is 4.000. In the same vein, a .450 OBP is much more impressive than a .450 SLG. Of course, teams need both to win, and power and discipline are both important factors. The fall-back argument on why the equivalent OBP is more impressive: would you rather have a team OBP of 1.000, or a team SLG of 1.000? Easy, the team OBP of 1.000 means you're never out. Granted, the value of SLG is not 4 times more inflated than the value of OBP, either. Different people assign a different factor to equate the two, but I'm personally fond of a simple 1.5 factor right now (Recent years, it was inflated a bit by a league-wide power surge, but the gap has closed a bit). That is, OBP * 1.5 will be about the equivalent number of SLG. It's not technically that simple, but it'll find values that are essentially close enough: .400 OBP = .600 SLG .380 OBP = .570 SLG .360 OBP = .540 SLG .340 OBP = .510 SLG .320 OBP = .480 SLG This is why I said "point for point". It takes more than one point of SLG to equal one point of OBP. Mathematically, it takes 4. In terms of evaluating individual players, 1.5 is as good an estimate as any. OBP is more valuable as a team statistic because the number of outs in a season is fixed, but the number of TPA is not fixed. I have 3 outs x the number of innings, which because of extra inning games and not batting in the bottom of the 9th at home, varies slightly, but either way, there's no way for me to get more outs than 3xInnings batted. I can, however, get more TPA by increasing my OBP because TPA=Outs+"Not Outs" (yes I made that word up), and "Not Outs"=TPA*OBP. I'll spare you the math, but moving the numbers around, you get TPA=Outs/(1-OBP). As you can see, as OBP goes up, TPA goes up as well. It then becomes obvious why this is so important. OBP increases the number of opportunities for something good to happen over a season, while simultaneously increasing the chance something good will happen in any particular AB. That's without even considering arguably more important effects like forcing a starter to throw a lot of pitches and getting into the pen sooner. SLG doesn't have the same sort of effect. It simply measures how affective a particular player is likely to be given a single AB. It is an excellent tool for comparing individual players, but does not have as profound a significance on the team level. But does your TPAs not go up with slugging as well? You have to have gotten on base to have a slugging percentage. In addition you have to have gotten on base via a hit and a high SLG means you are getting exta base hits. In addition many of the anciliary effects, because again you are still getting on base, would be the same, I think, and players are more likely to be in scoring position (or in case of a HR already scored) putting even greater pressure on the pitcher.