I haven't seen any "injury history" to it but it seems like it would make complete sense if you ask me. Throwing a fastball overhanded is hard enough on the arm, I can not believe that throwing it sidearm can be all that healthy for your elbow joint, either. Curiously, here's a list of side-arm throwers in MLB, according to wikipedia: "Sidearm pitchers are fairly rare, but many have succeeded in the major leagues, including Scott Feldman, Pat Neshek, Scott Sauerbeck, Dennis Eckersley, Mark Eichhorn, Javier López, Jake Peavy, Dizzy Dean and most notably Walter Johnson." Yep, some of those threw side-armed but not Feldman. Or Peavy. At least not that I know of. Eckersley did as a reliever but I don't recall when he was a starting pitcher for the Red Sox or Cubs that he threw side-armed. Walter Johnson did, but not much video really exists of him except for him throwing side-arm while warming up prior to games, so who knows how much side-arming he really did? I'm just saying, as a lefty who tried it a few times in high school, after about 40 or so throws like that, my elbow was hurting. Nothing major, of course, but I went back to regular overhand throwing. And, yes, someone is bound to argue that "you were just some high school player, not a major league player." And, while this is true, I still can't bring myself to believe that a manager, pitching coach, trainer, or team physician would not cringe a bit if a side-armer told them they want to be a starting pitcher. Seriously, I can't think of one side-arm throwing starting pitcher in the major leagues in the last 10 years. Ah crud, I just did. Byung-Hyun Kim. But his starting pitching was disastrous (pretty much led to him being out of baseball) and he did it only part time (most remember him as a reliever.) Here's more names of current side-arm/submariners in MLB, according to Wikipedia: * Chad Bradford of the Tampa Bay Rays * Randy Choate of the Tampa Bay Rays * Daniel Davidson of the Los Angeles Angels of Anaheim * Joey Devine of the Oakland Athletics * Pedro Feliciano of the New York Mets * Brian Fuentes of the Los Angeles Angels of Anaheim * Sean Green of the New York Mets * Byung-Hyun Kim is a Free-Agent * Mike Koplove of the Pittsburgh Pirates * Javier López of the Boston Red Sox * Carlos Marmol of the Chicago Cubs * Jay Marshall of the Oakland Athletics * Cla Meredith of the Baltimore Orioles * Matt Miller of the Cleveland Indians * Peter Moylan of the Atlanta Braves * Mike Myers is a Free-Agent * Pat Neshek of the Minnesota Twins * Darren O'Day of the Texas Rangers * Josh Papelbon of the Boston Red Sox * Clay Rapada of the Detroit Tigers * Chris Schroder of the Washington Nationals * Brian Shouse of the Tampa Bay Rays * Joe Smith of the Cleveland Indians * Joe Thatcher of the San Diego Padres * Ehren Wassermann of the Chicago White Sox * Brad Ziegler of the Oakland Athletics * Shunsuke Watanabe of the Chiba Lotte Marines * Lim Chang-Yong of the Yakult Swallows * Chong Tae-Hyon of the SK Wyverns * Liao Yu-cheng of the Brother Elephants Notice that every single one of them is a reliever.