(Katherine Frey/The Washington Post)

You often see or hear comments about certain players and wonder if they are actually true. For instance, perhaps the No. 1 cliche about Nats hitters may be that Ian Desmond is a “first-pitch fastball hitter” and that this is a key to his excellence the last two years. You even see comments that he’d be better if he weren’t such a fastball hunter. Well, is it true? These days, you can get tapes of every home run hit in MLB as well as the pitch type and speed of every pitch in every game. There’s much more. But 15 minutes of simple film study can show you that the conventional wisdom on Desmond is not just wrong but backwards.

Of Desmond’s 20 homers this year, 17 have come on off-speed pitches, only two on fastballs (93 mph from Ervin Santana and 89 from Manny Corpas) and one on a cutter from Edwin Jackson (91). None of his homers have been on first-pitch fastballs. He looks for breaking balls with two strikes and almost half his homers are on those pitches. He kills low breaking balls. The speeds of the other pitches on his homers: 79, 84, 88 (slider), 72, 83 (Jeff Samardzija), 73, 85, 83, 83, 83, 80 (Patrick Corbin), 85 (Matt Harvey), 81, 85, 83 (Tim Lincecum, high hanging curve, 448 feet), 88 (slider), 86. Fastball pitchers like Harvey and Jake Peavy must want to kick themselves after giving up off-speed bombs to him. Desmond has only one home run to the right of dead center field — that was a bad Corpas fastball up and away.

Desmond does hit fastballs. He just doesn’t pull them in the air for power, except the one off Santana that almost landed in Kansas. You hear about the league adjusting to tendencies, then the hitter adjusting right back. That may be happening now. This, of course, is guesswork. It seems Desmond is firing more fastball hits to right field and center field recently. In his last 15 games he only has one homer but is hitting .355. Maybe he’s teaching them a lesson. They’ll have to go back to breaking balls more often. Desmond, who is about as smart as they make ’em, will probably be waiting.

This year Desmond’s runs above average (Pitch/FX) are best against change-ups and sliders. His whole career is similar. He has negative value vs. an average hitter on fastballs. Yet the league still doesn’t throw him many fastballs (only 57.7 percent — most are above 60 percent). Baseball is more fun these days because you can actually find out which bromides are true and which, like “Desmond has become a good hitter because he’s now so good at attacking first-pitch fastballs,” are mostly false.