Pitcher as Fielder

In response to Matt's post about near-Perfect games, jl25and3 wrote

"I'll disagree with you on Dick Bosman. The pitcher-as-fielder is considered separately from the pitcher-as-pitcher, and that's the way it should be. You're judging his pitching performance, and his fielding isn't relevant.

Think of it this way: if a batter reaches on a pitcher's error, would you count that in the pitcher's DIPS? Of course not, because it had nothing to do with his pitching.

Once the ball is hit to him, he's no longer a pitcher. He's just another infielder. That infielder's bad play shouldn't affect any evaluation of the pitcher's performance."

I started to write a response but then figured it deserved it's own post. I disagree strongly with jl. The purpose of the pitcher is to prevent the other team from scoring runs. It is extremely arbitrary to say his job as a pitcher ends as soon as the ball leaves his hand.

If a pitcher is a complete liability on defense then he cannot be a successful pitcher. A pitcher who can pitch well but cannot field his position isn't any more useful to his team than a pitcher who can't pitch well. I'd argue that batters who get on base due to errors by the pitcher should count as earned runs if they come around to score and should count toward a pitcher's WHIP(more reasonable to make a new stat called WHEPIR Walks + Hits + Errors by Pitcher / Innings Pitched).

Let's consider 3 possible results from a 3-2 count.
1) The pitcher misses the zone and the batter walks.
2) The pitcher leaves the ball up and the batter gets a single.
3) The pitcher makes a decent pitch and the batter hits a dribbler to the mound. The pitcher misplays it and the batter gets to first.

Scenarios 1 and 2 are considered the pitcher's fault as a Pitcher. In scenario 3 it's considered the pitcher's fault as a Fielder. In all three the batter is on first due only to the actions of the pitcher. I don't see the purpose of separating pitcher's pitching statistics and pitcher's fielding statistics outside of a thought experiment. The pitcher's job before he pitches is to prevent runs and the pitcher's job after the ball leaves his hand is to prevent runs. The player who throws the ball to the catcher and the player who fields the 1 position are one in the same so why should stats treat them as different people?