MLB recently had an article on "my boy" John Patterson. Seems they believe, as was noted by a big orange fellow previously, that he has two sides. However, they kind of gloss over the real reason, implying that the injury effected his stamina in some way. The pitch counts don't seem to reflect that. He was roughly pulled at the same time frame before or after the injury, maybe even left in longer after.
The real reasons for his dual nature are the simplest of pitching problems. Too many walks, too many HRs. So why do I like Patterson so much, if he keeps giving out free passes and dingers? I has to do with pitching philosophy.
Walks are like dust in the wind, Soh-Crates. If you have good stuff, they kind of blow away at the end of each frustrated at bat. They will limit your effectiveness to go deep into the game for sure, but these grains of sand don't matter if they don't cross the plate. You keep the ball out of play, the chances of them reaching the plate are limited. Many a power pitcher has been high up in the league in walks and continued to be very effective. I don't like walks, but for a strikeout pitcher, I can accept them.
Home runs are much more of a problem. If you are leaving men on base giving up more than the occasional dinger will kill you. For example, if you look at Randy Johnson's worst two years, 1996 and 2003, they correltate more closely with giving up more HRs than giving up more walks. (in fact 2003 set a personal best for control for the Big Unit, only to be bettered in 2004). Looking at the worst 30 HR giver-uppers, Patterson ranks 8th in the NL giving up over 1 and a half HRs a game. But this strikes me as a easier problem to correct than control. Just keep the ball down, forget about the strike zone.
I'm probably being overly optimistic here but I think if Patterson can keep the HRs down to a reasonable level, say a little more than 1 a game, that he will not only be an effective pitcher, he'll border on All-Star level. He's got stuff on par with Beckett, Clement, Wood, a notch below the elite.
If only he gets the chance to pitch...