There have been times this season when Boston Celtics coach Brad Stevens has seemed downright apologetic about having to keep Tyler Zeller glued to the bench. It's easy to forget, but Zeller didn't just appear in all 82 games for Boston last season. He started 59 of them, including the final 30 games of the regular season -- as Boston surged to the seventh seed in the Eastern Conference -- and all four playoff games against the Cleveland Cavaliers team that traded him to Boston.

The 26-year-old Zeller entered Tuesday's game against the New York Knicks having logged 18 DNP-CDs (did not play-coach's decision) this season, including his most recent on Sunday in Orlando. Even as Stevens has leaned more heavily on a nine-man rotation recently, Zeller had appeared in Boston's six previous games, though four of those games were stints of seven minutes or less.

In need of some additional size and rebounding against phenom Kristaps Porzingis and the Knicks on Tuesday in New York, Stevens turned Zeller loose for a season-high 26:32 -- his longest appearance since April -- and the 7-footer responded with his first double-double (16 points, 10 rebounds) in over a year.

"There's not a person around that's not happy to see him do that," Stevens told reporters in New York. "He has sacrificed quite a bit throughout the whole season for our team. We really trust him, and he played great tonight."

The Celtics spent much of the first half clanging 3-point shots (0-for-13 beyond the arc over the first two quarters), and Zeller provided a much-needed close-range jolt. Not only did Zeller connect on eight of 13 shots overall, but he was 6-of-8 shooting near the rim. Boston owned a team-best offensive rating of 112.6 during Zeller's court time, and that was 11 points higher than the team's rating overall. What's more, Zeller grabbed a staggering 29.2 percent of all offensive rebounds -- which was an even greater percentage than the Knicks' Robin Lopez, who had 11 offensive rebounds in 37 minutes.

Not bad for a guy who has had to use off-day workouts to get in the cardio he has been missing on the court.

Teammates showered Zeller with praise after Tuesday's game. Jae Crowder told reporters that "[Zeller is] being a professional. He’s being the best professional I ever saw. ... To just stay locked in and stay the course, coming in every day and working, my hat's off to him and I applaud him. It’s big."

Stevens couldn't help but gush about his fellow Indiana native and how he has stayed ready despite a crowded frontcourt that has left both Zeller and David Lee (17 DNPs, including 12 straight currently).

"[Zeller is] always ready. I have so much respect for him and, in the same vein, David," Stevens said. "The way they prepare every single day, the way they go about it, it's been great to see and, again, you root for guys that do that. And certainly he's done that."

The Celtics have now won nine of their past 12 overall and have wiggled into a tie with the Atlanta Hawks for third place in the Eastern Conference. There is always the chance that Zeller will quietly slide back into his "break glass in case of emergency" role, particularly on nights when starting bigs Amir Johnson and Jared Sullinger are more consistent than they were against the Knicks.

But watching Zeller thrive in the pick-and-roll with fellow fourth-quarter hero Evan Turner bodes well for how fast Stevens is likely to go back to him when the coach needs some size. Even in small chunks of minutes lately, Zeller seems to have regained his touch around the basket, and some of those layups and bunnies that used to rim out are falling in now.

Zeller is in a fascinating situation. There were some back in October who wondered whether the Celtics should throw out a contract that could have scaled to eight figures in order to lock up Zeller before he reaches restricted free agency this summer. With a lot of money available around the league, it's unclear what sort of offers Zeller might draw, but performances like this remind the rest of the league what he is capable of.

For the season, Zeller is averaging 4.8 points, 2.5 rebounds and 0.3 assists over 9.4 minutes per game. The Celtics' offensive rating is 7.3 points per 100 possessions better when Zeller is off the court. A small, sporadic sample size might be at work here, but Zeller showed on Tuesday night that he's capable of being an impact player.

And he's shown this season that he's going to be ready whenever Stevens calls on him.