This is a baseball term coined by a popular baseball blogger. It refers to a pitcher who can pitch for approximately 200 innings a season while pitching no better or worse than the league average. This type of pitcher is like a workhorse for the team and is expected to help carry the load and support the team. However, they are rarely expected to win the game for the team. Such a pitcher is not considered bad, in fact, these types of pitchers are useful and necessary.
The acronym was coined by baseball blogger Travis Nelson when describing a team's signing of pitcher Jeff Suppan. The phrase has appeared in the 2011 Baseball Prospectus, but has not made it into the parlance of everyday baseball discussions. The LAIM moniker is still mostly used in sabermetric circles and other extreme baseball fans.