Matsuzaka (elbow) threw an extensive bullpen session Tuesday that likely will preclude him from starting for Brooklyn of the New York-Penn League on Thursday. In addition, there is a good chance he is activated prior to September 1, ESPN New York reports. Matsuzaka has looked good in his rehab starts and had no problems with his injured elbow. The Mets may go to a six-man rotation in September to give Jacob DeGrom more rest and enable Rafael Montero to see some starts. Dice-K may be part of that rotation but also work out of the bullpen the last month of the season.