As suggested by the 9.74 ERA he recorded over 44 innings in the California League this season — or even his most recent start in the Arizona Fall League, during which he conceded six runs over 4.0 innings — Houston right-hander Mark Appel’s professional career hasn’t been entirely free of difficulties. That he continues to exhibit promise, however, is still very much the case. And that he’s capable still of throwing a slider with what is known alternatively as “two plane break” and “furious pleasure” — that he’s capable of doing so is made evident by the footage above, of Appel throwing that same breaking pitch to Washington catcher prospect Spencer Kieboom in a different AFL game currently underway and available by way of MLB.com.