His legs were sore and his mind was exhausted, and he acknowledged sleep sounded pretty darn good.
The 6-foot-7, 225-pound red-shirt junior forward, who made his Rutgers debut in the season-opening win, also knows coach Fred Hill wants more from him, beginning with Friday's contest against Drexel at the Rutgers Athletic Center.
Mitchell sat out the NCAA-mandated one year after transferring from Florida, and debuted by playing a career-high 31 minutes. He was 3 of 6 from the field and finished with nine points and four rebounds.
"Jonathan was very, very solid.'' Hill said. "Was it what I expected out of him? I expect more out of him. I think he had four rebounds. I expect him to be a little more physical, a little tougher. We talked about it.
"Offensively, it's very good. …I don't want to get greedy, but he's capable of getting six or seven rebounds for us, and he's going to have to do that for us to be a good defensive team.''
One of the issues Mitchell faced on the boards was the play of teammates Greg Echenique and Hamady Ndiaye. The two centers combined for 13 rebounds in 39 minutes.
"I definitely thought I brought a lot of energy,'' Mitchell said. "I thought I was active, but it's hard when you've got big H and Greg down there grabbing all those rebounds. I'm definitely going to talk to coach, and if he wants me to grab more boards, that's something I'm going to work on.''
Rebounding aside, Mitchell showed his basketball IQ by moving the ball quickly and finding the open player. He made his only 3-pointer and looked comfortable in his role as a calming on-court influence.
However, the rust of sitting out a season also was evident as he works to getting his mind and body back into playing shape. On one play, Mitchell was open when he caught the ball at the foul line, but hesitated before moving forward and missing a short jumper.
"I've never played that many minutes before,'' said Mitchell, whose last game was a seven-minute stint April 1, 2008. "I'm still getting adjusted. I'm going to have to hit the treadmill more to get in a little better shape, but I think that will come as I keep playing.''
As the season progresses, Hill hopes Mitchell's versatility creates defensive issues for opponents. Mitchell has the foot speed and range to play on the perimeter, and the strength, size and savvy to play in the low post.
But against a Marist team that went small, Mitchell wasn't able to showcase that aspect of his game.
"He's a mismatch,'' Hill said. "You've got a four-man that can really play the three, and step out and stretch the defense, and knock down threes and take you off the dribble, and (he) knows what to do. He's going to give some people some problems.''