Jason Bay, who has been on the 15-day disabled list since April 24 with a fractured rib, met with team doctors last night at Citi Field and was cleared to resume some baseball activities. "It hasn't been determined how much and what they're going to be, but I'm sure they'll be rotational exercises to start to get his core back to strength,'' manager Terry Collins said. The left fielder eventually will have to play in some minor league rehab games, and Collins estimated Bay could be back in 7-10 days. "I start [today],'' Bay said. "Just ramping up, anything that's tolerable, running, hitting, everything will be a progression. They just said if something bothers you, don't do it.''