I agree with Dan about the differences between OOTP and DMB. OOTP is great if you want to create a baseball universe - majors and minors - and have it run for 100 years with players coming in to the minors, developing their skills, hitting the majors, and then declining to retirement. And the new OOTP06 is going to expand that on a grand level to include things like winter leagues, international play, Arizona fall leagues, more minors, etc.
But it lacks head-to-head play capabilities (and from what I understand that may still be true in the new version), which is perhaps the best feature of DMB. If you want to manage your team game in and game out - pitching changes, pinch hitting, double switches, the whole Dusty Baker experience - then DMB is your game. If you want to take control of an organization like a GM and run the finances, the draft, sign free agents, etc., then OOTP is the better choice.
I’m in one OOTP league and one DMB league, and I like them both. They just do very different things.