If you're Frank Howard you swing for a line drive and often it ends up a homerun, but few of us are Frank Howard. Or if you have a superhuman physique like Mantle, who often swung for line drives, that ended up homeruns (and Mantle also sometimes swung for the fences, and if he connected it was a 500 foot homerun but usually it was a strikeout). And maybe Harper is in that superhuman category, I don't know, but I do know that Desmond isn't. In order for Desmond to hit a homerun he has to go into near-uncontollable-swing mode. When he does that, which is nearly every time he swings, then if he is lucky to make solid contact it's a homerun. But by swinging like that, he lowers his chances of making solid contact (or even any contact at all).
No I'm not saying Desmod should try to place the ball nor am I saying it's pitch selection in his case/ He isn't that type of player. For Desmond, I suppose as you say don't try to put it in the air would be a good start. I would be even happier if he would concentrate more on making hard contact with two strikes.
We used to call it "meet the ball" and "don't swing from the heels". Guessing that Ray is like me: old enough to have seen Mickey Vernon, Roy Sievers, Pete Runnels, and Harmon Killebrew. Roy and Mickey had a smooth swing...hit line drives without falling down when they swung.
If I was King of the Nats, and if Desmond was signed for the next couple of years, I'd send him to Mike Epstein to learn the Ted Williams method of hitting.
Clutch hitting? Hittimng when the pressure is on. Joe Panek did it to the Nats, and so did Pablo Escobar.
I don't think stats have disproven clutch hitting. Don't think they have disproven the bunt with a runner on 3B and one out. I don't think highly of the "pitcher's bunt", where the hitter -- often a pitcher -- squares up as the catcher gives the sign. The skilled bunt is something else.