Just did a long post about historically good hitters who almost all had a 10-15% platoon advantage. Then it was erased somehow. Arrrrgggh.
Mays, Aaron, Dick Allen, Piazza all had about 100 pt OPS differences.
McCovey and Boog Powell were about 140 pts. Thome was 300 pts. Junior was 90 pts. Reggie Jackson was about 100 pts.
Edgar was only 55 pts and Billy Williams had a 100 pt reverse split.
I picked them all at random and haven't left anybody out. That was the entire list of historic guys I looked up. Surely some people run nearly zero split difference. Edgar wasn't at zero...but had a reduced platoon advantage. Billy Williams was just weird. A mashing, RH hitting Aoki.
But if some of the best hitters ever (and a bunch of those guys are in the Hall) show split differences why should anybody think it isn't "real?" If you're going to say that 100 pts appears to be the normal split difference that is fine....but some guys clearly aren't normal. Lind hits LHP at a career .589 rate. Brendan Ryan hit lefties at a whopping .636 number (he was 40 pts worse against RHP). When you run Lind out to 1B vs. lefties, you're essentially putting Brendan Ryan there, sans all the glovey things he did.
Now why wouldn't you platoon in such a situation, given a partner for Lind (260 pt split difference)? Lind has 1000+ PA's vs. LHP. He hasn't been "unlucky" vs. them. He's just not very good.
For some people the split difference is negligible. For some it doesn't make much difference. Hey, Willie Mays laid waste to RHP's, too. The Giants didn't carry a 4th OF who hit RHP better than Willie. But for many MLB players there is a real difference, one that counts. All things being equal, if you can platoon them to good effect then do it.
It's harder to do it with a Seager (108 pts better vs RHP...but still at .711 vs. LHP) because he brings a glove premium, regardless of the handedness of the pitcher.
A Lind doesn't really do that. Nor does a Seth Smith (230 pt difference).
Every team carries a 4th OF...if they give you a split advantage you SHOULD use them. Few teams, for example, carry (specifically) a 2nd 3B (although the Mets in '69 largely used a 3B Platoon: 1B, too).
Differences exist...and some guys have them that are beyond the norm. It just is.
Keith