While the Celtics played their 41st game on Jan. 4, the trip to London seemed like the true midpoint of the season.

Which means it’s time to hand out some midseason grades for the 34-10 Celtics, who own a three-game lead for the top seed in the Eastern Conference and have beaten every serious contender for the NBA title at least once.


Kyrie Irving: B+

I have him somewhere between an A- and B+, but because we all know he can be an A+, I’ll go with the lower grade. He’s been spectacular on offense, averaging 24 points and five assists a night while coming close to shooting 50-40-90 (he’s at 48-39-89), the benchmark for elite efficiency. The reason he’s not bringing home an A to slap on the fridge is his defense, which started the season strong but has slipped in recent weeks. He gets caught on too many screens — if he’s not ducking under them — and gambles for too many steals, sometimes getting caught in no-man’s land in the backcourt and just jogging back up. All of it is fixable, and he brought better energy early in the season, which makes me think when the games ramp up, Irving’s defense will as well.

Al Horford: A-

Horford has looked even more comfortable in his second season in Boston. He and Irving have developed a strong two-man game, and the Celtics have found offensive success playing through Horford in the high post. He’s in the running for All-Defensive first team and is shooting a blistering 42 percent from deep and 52 percent overall. So why not an A? Because he still shies away from the big post players of the league. He’s not comfortable as a true center, having to guard the Marcin Gortat’s, Andre Drummond’s and Hassan Whiteside’s of the league. And when he’s struggling to match up with those guys on the glass, he lets it affect his offensive tenacity.

Jaylen Brown: A-

His offense has been a revelation, averaging about 14 points and six boards a night while shooting better than 46 percent from the floor and 39 percent on 3s. He’s become the third offensive option the Celtics thought they’d be missing when Gordon Hayward went down, and he adds a level of athleticism the team hasn’t seen since young Gerald Green. He’s a strong one-on-one defender, although he struggles when switched onto stronger power forwards. He’s improved his team defense, getting lost less often on the weak side and communicating better on switches. The only thing keeping him from an A is his consistency. He’s topped 20 points nine times, but has also scored in single digits 11 times.

Jayson Tatum: A

Tatum has done everything you could expect out of him and more. He’s a better shooter, a better finisher and a smarter player than I saw coming out of Duke. He can play on all three levels offensively: At the rim, in the mid-range or behind the arc. He’s always in the right place, makes smart cuts and doesn’t let the ball stick in his hands, a big fear considering his size-em-up style in college. His defense has been hit-or-miss, but he shows promise and it’s hard to find a guy who came into the league as an elite defender (although we’ll get to one shortly).

Marcus Smart: B-

This grade is more based on what I thought he could be this season than anything else. I drank the Kool-Aid in the preseason, when his slimmed-down body and rejuvenated back led to a significant uptick in his shooting. Turned out, it was a small sample size. Smart is back to being the same player he was the last two — I’ll allow his passing has improved — a defensive savant with no effective offensive game (he’s shooting 34.6 percent overall and 29.3 from 3). There’s a role for players like that, whether it’s Andre Roberson, Thabo Sefolosha or Luc Mbah a Moute, but they’re usually taller swingmen then 6-foot-4 guards, and they can usually be had fairly cheaply on the free agency market.

Marcus Morris: C-

On his best days, like against the 76ers on Thursday when he scored 19 points, he can be another solid swingman who shoots well, defends a few positions and grabs a few rebounds. But he’s so rarely had those good days this season. Between legal trouble and a bum knee, Morris has played in just 22 of 44 games. But more than that, what concerns me is his reticence to play the Celtics’ brand of basketball. While Tatum was able to quickly adjust his game to Brad Stevens’ arc-and-rim preferences, Morris still falls in love with step-back mid-range shots or turnarounds. He struggled defending LeBron James last week, eventually ceding duties to Semi Ojeleye and Horford. He also seems to be stewing over not starting consistently and is the last guy in the locker room you’ll see crack a smile.

Terry Rozier: A-

Along with Brown, Rozier has been the most improved Celtics player. A couple of years ago he was hitting less than 30 percent on 3s, this year he’s up to 37.2 percent. He’s finally learning how to harness his speed and athleticism into the halfcourt, and his confidence has been soaring. The Louisville product has improved every season in the league and there’s little reason to believe he won’t continue that progression.

Aron Baynes: C

Baynes gets a passing grade, but nothing above average because that’s just about the type of player he’s been. He does little wrong, but he rarely provides significant contributions. He can rebound and battle against big bodies and occasionally hit a mid-range jumper, but his hands are a little brick-ey, he doesn’t run the court well and he can’t switch onto smaller players and stay in front of them. He didn’t turn out to be much of an upgrade over Amir Johnson.

Daniel Theis: B+

While Baynes is very much a “he is who he is” type of guy, Theis, a 26-year-old rookie, has shown flashes of an intriguing skill set. He’s already the team’s best offensive rebounder (on a per-minute basis), he plays hard, runs the court and has even flashed a little long-distance shooting upside, although he’s hitting just 24 percent from deep. His 15.0 PER is fourth on the team behind Irving, Horford and Tatum. Inch that 3-point shooting up to 30 percent and I’ll happily give him an A.

Shane Larkin: C

We’re getting deep on the bench here, so if your fourth point guard is just average, that’s more than acceptable. He’s quick, is a streaky shooter and has provided some sparks off the bench, but he’s not a guy the team will, or should, rely on come the postseason.

Semi Ojeleye: B-

I debated this grade more than any other, but decided in the end that if Smart gets a B- as a premier defensive player with significant offensive liabilities, it’s hard not to give Ojeleye the same mark. His quick feet and long wingspan make him the prototype of a wing defender, and he’s shown the hustle and energy to fulfill that potential. Now he just needs to develop an offensive game. He’s shooting 28.8 percent on 3s and 31.2 percent overall, although about three-quarters of his shot attempts have come from downtown. If he even develops Jae Crowder levels of offensive aptitude, a 3-point shot and sprinting down the wings in transition, he’ll carve out a nice NBA career.

Abdel Nader/Guerschon Yabusele: Incomplete

They haven’t shown up to class enough to give them a grade. Nader can score, but also looks overwhelmed at times. Yabusele has shown some hustle, but not a lot in the way of skills. They’re both averaging less than eight minutes while playing in less than half the Celtics’ games.

Brad Stevens: A+

Could you do a better job than Stevens has done this year? I think even Gregg Popovich would struggle to surpass Stevens’ results. He always seems to play the right card at the right moment, the players respect him and he gets results. If a coach was every eligible to win league MVP honors, you could easily make a case for Stevens.

Danny Ainge: A

The Celtics' President of Basketball Operations somehow managed to navigate the downturn between championship teams with nary a hiccup. Five years after a first-round exit with Kevin Garnett and Paul Pierce, he had the Celtics back in the Eastern Conference Finals. Then he wasn't afraid to blow it all up in the name of progress. He still has one more top lottery pick on the way, and all his own first-rounders going forward. About the only thing he hasn't done is turned Gordon Hayward's $8.2 million injury exemption into something useful, but he still has a month to work on that.

Follow Brendan Kurie on Twitter @BrendanKurieSCT