As promised, here's Carlos' PFX breakdown. The full breakdown is on Fantasy Baseball Strategy. If you want a quick summary, read on below.
Carlos appears to have slightly changed his delivery in his last start. He seems to have dropped down, causing excess stress on the shoulder and elbow. In the series graph, you can also see how it wavers horizontally. This can also mean several things, most notably that he's dropping his shoulder or releasing the ball late in his motion, both of which can cause injury.
His velocity was off in his last start with almost every pitch but his pitch command wasn't. Normally the first sign of injury is loss of command but I think this is only in cases where the condition doesn't happen all at once, where it occurs over time. This didn't happen to Zambrano. He described it happening all at once, so the pitch location chart isn't very relevant to this discussion.
Finally, his movement was the same basically, there was some small shift to the left but no change in the vertical distribution.
Summary: There are some signs that he was beginning to change during the game which may have caused his injury. Do we have enough yet to definitively prove this, not quite yet. With more analysis, though we may eventually get to that point.
