IMO the game was more than playable online last year. Played almost 200 games and experienced bad lag maybe 5x. I'd check your ping response time on a speedtest. Higher the #, the more lag you might experience.
As far as making online better...
MLB 13 Online Leagues Overhaul (PS3) -
This year with MLB 13 The Show Online Leagues has been given a complete and total overhaul. New features include being able to play the real MLB schedule with all 30 teams, coupled with upgrades and refinements – like being able to manually control the pace of the league. Ultimately, the commissioner of a league will have the tools to be able to create and customize it in order to play with anyone anywhere to have a complete MLB experience in an online environment.
24.
Pitcher Energy/Rotations for Online Play Now
25. Mercy Rule for online games
27. Ping indicators in online game rooms
28. New online ranked game Play Now flow with game worth
Looks good to me.. March 5 yet?