Why is it called the bullpen?

Answer 1

This is from Tim McCarver, so take it with that in mind, but he said that it was born from a comment that an announcer made early on. He said "They look like bulls waiting to be let out of a pen," referring to the relief pitchers.

More input from WikiAnswers Contributors:

• Apparently it is because a long time ago, they used bulls for entertainment and they kept them there.
• The game was played out in the fenced in areas of fields where the cows and bulls ate the grass making it the ideal place to play ball. Off to the sides was a very much smaller fenced-in area where the bulls where kept when the farmers didn't want the bulls grazing. This is where other pitchers warmed-up ... out of the field of play.
• Bull Durham tobacco used to be advertised in Baseball stadiums, notably in and around (a) the outfield fence and, as a particular subset of (a), (b) the area where pitchers would warm up. That's the brief, vague-ish version, but it's essentially the correct one.
• "Bullpen" has nothing whatsoever to do with actual bulls.
• Etymology (i.e. genealogy for words) is a notoriously inexact science.The most common explanation for the origin of the term "bull pen" seems to be that Bull Durham chewing tobacco was advertised in that area of the field.
• I have heard the term came from old small Midwest ball-fields built on farms and near old small western rodeo arenas. They used the old pens where the bulls were kept for the relief pitchers to warm up in, i. e. the "Bullpen".
• It is called a bull pen because in the early day's they had baseball fields and farms and the pitcher would warm up in the same pin as a bull. This would get there adrenalin going and get the pitcher ready.

Answer 2

It’s called a bullpen because it is for the pitchers to practice!DUH!