Name the only MLB player ever...

[Guest Bret Sabermetric]

with a four-syllable name, every one of which is a human body part.

[seawolf17]

That would, of course, be the great Phillies pitcher, Steve Heartlegarmhead.

[Valadius]

I'm guessing "knee" is part of it, as in Rodney or Barney or something.

[Guest Bret Sabermetric]

Correct. Three body parts to go.

[Valadius]

Jaw + Knee = Johnny?

[Guest mt8thsw9th]

Bret Sabermetric wrote: with a four-syllable name, every one of which is a human body part.

Tony Armas.

Toe, knee, arm, ass.

[Valadius]

DAMMIT, DAMMIT, DAMMIT, I only JUST figured Tony Armas out.

[Guest Bret Sabermetric]

Bingo!