This one in particular might have something to do with MVP Baseball 2005 being the last of the series due to the MLB and Take-Two having exclusive rights preventing EA from making future MLB games until this year.
So my guess is that EA was allowed to keep selling MVP BB 2005, so they just dropped the 2005 from the title so gamers might not realize how old a game this was since no new ones had been made since.
Edit: Well maybe not, since the date was only dropped from the spine and not the cover as well. Hell I dunno, but I wouldn't be surprised if it was related to all that.