Gronkowski has been practicing for several weeks, and a source said there is a 50-50 chance that he makes his return to the lineup Sunday against the Tampa Bay Buccaneers.
Although the Patriots have opened with two victories, Brady has been visibly frustrated after struggling with a supporting cast that includes three rookie wideouts and an undrafted rookie tight end.
With three top receiving targets missing last Thursday, Brady struggled throughout a 13-10 victory over the New York Jets, completing less than 50 percent of his passes and running an offense that converted just 4 of 18 third downs and had more punts (11) than first downs (9).
That could all change with Gronk, who is the NFL's most dominant red zone player. He missed the entire preseason and the first two regular-season games following offseason surgeries on his back and forearm.
On Monday, in his weekly interview with WEEI Radio in Boston, Brady compared Gronkowski's absence to a baseball team losing its ace pitcher.
"He's a great player and he helps in the run game and the pass game, provides a level of toughness for our team, and he's been a really consistent player when he's been out there, so it's really -- it's hard to replace him; there's only one Gronk," he said. "I know he's working his butt off to get back, and every time I see him he's got a great attitude about his rehabilitation and what he's going through to get back on the field."
Patriots offensive coordinator Josh McDaniels was asked Tuesday how the team's game plan would change if Gronkowski is back in the lineup.
"I don't know that it would affect the groupings that we would use or not use ... or whether we would use our tempo or not, you know, I don't know that would really be impacted," McDaniels said. "But I definitely think that you'd like to have a guy like that on the field as much as you can if he's ready and able to contribute in the way that Rob has been able to."
ESPNBoston.com's Field Yates contributed to this report.