Jim O'Brien arrived in Miami yesterday on an outreach mission that could go a long way toward defining the Celtics' frontcourt needs next season.

The Celtics coach was scheduled to have dinner with Vin Baker last night, then watch the Celtics forward work out today.

Baker, who left the team last season to deal with alcohol-related health issues, has taken part in what has been described as an intense workout regimen this summer in an attempt to resurrect his NBA career.

Baker, who turned down the Celtics' offer to play in last week's summer league, has instead been working out this month under the supervision of Alonzo Mourning's trainer in Miami, reportedly with impressive results.

O'Brien, who gets to see for himself today, agrees with the reports that Baker has attacked his workouts with a hungry, relentless approach.

``Absolutely,'' O'Brien said yesterday. ``And I expected nothing less. He really set up an aggressive schedule for himself.''