Countdown to training camp: Options are plentiful at center spot

This is part of a new BSJ series, designed to get you ready for training camp. Each day, we’ll take a look at each particular position on the depth chart and what to expect from each player before the season begins.

Today: Center

Overview: One year after entering training camp with plenty of uncertainty in this area, this is looking like one of the deepest parts of the roster. The starter will likely be Al Horford on many nights, but don't discount the possibility Aron Baynes gets the nod for more than a handful of contests after forming one of the best defensive combos in the league with Horford last year.

There are a high number of traditional centers in the East (Dwight Howard, Andre Drummond, Jonas Valanuncinas, Joel Embiid, Tristan Thompson) the Celtics would be wise to protect Horford from during the regular season grind, and Baynes is the ideal player to do that for 15-20 minutes per night. Starting Baynes situationally would also give Stevens the freedom to play Daniel Theis at center with the reserves. On nights Baynes and Theis both come off the bench, it's going to be hard to give them both regular rotation minutes since it's not an ideal look to play that tandem together as a power forward/center combo, given how much Stevens values versatility on the defensive end.

Horford will be the closing center on most, if not all nights. The Celtics are well positioned to give him nights off and protect him from the wear and tear of the center position for 20-25 minutes a night. Whether or not they do so remains to be seen.

THE STARTER: Al Horford
CONTRACTUAL STATUS: $28.9 million for 2018-19, player option for 2019-20 ($30.1 million)
ELIGIBLE FOR FREE AGENCY: Next summer if he declines player option
NOTABLE 2017-18 STATS:  12.9 PPG, 7.4 RPG, 4.7 APG
ASSESSMENT: The 32-year-old has been Mr. Everything for the Celtics for the last couple of seasons, but the burden on him, at least on the offensive end, should start to fade this year with the return of Gordon Hayward and Kyrie Irving. That won't make him any less of an integral part of the team's title aspirations. Very few guys can defend like him and shoot at an elite level from 3-point range. Those open looks from downtown should only become more plentiful given the weapons around him. The key for Stevens with Horford will likely be to ensure he's peaking by the time April and May rolls around. We saw some strategic rest last year, but there should be even more rest for him with a healthy supporting cast in place backing him up. His numbers will steadily decline with the reduced minutes, which should draw some extra scrutiny for him, but that chatter should be ignored as long as this group keeps winning. Most teams around the league would love to have him despite his high price tag.

THE SPOT STARTER: Aron Baynes
CONTRACTUAL STATUS: $5.2 million for 2018-19, player option for 2019-20 ($5.5 million)
ELIGIBLE FOR FREE AGENCY: Next summer if he declines player option
NOTABLE 2017-18 STATS:  6.0 PPG, 5.4 RPG, 1.1 APG
ASSESSMENT: The Celtics brought back the best defensive big man on the market at a relatively team-friendly price this past summer. Whether or not his elite 3-point shooting from the postseason (47 percent) will carry over at all remains to be seen, but he'll be an important part of the rotation regardless, as he battles the likes of Embiid, Drummond and other true centers on a nightly basis. He holds a no-trade clause (due to his one-year deal) so don't be throwing him into any offers during the year (he loses his Bird Rights if he gets dealt). The question of how much he plays likely depends on whether he can remain a net positive on offense in his limited minutes.

RESERVE: Daniel Theis
CONTRACTUAL STATUS: $1.378 million for 2018-19
ELIGIBLE FOR FREE AGENCY: Next summer. Will be a restricted free agent, assuming Celtics make him a qualifying offer
NOTABLE 2017-18 STATS: 5.3 PPG, 4.3 RPG, 0.9 APG
ASSESSMENT: The German native will enter training camp fully recovered from a torn meniscus that has repaired last March. One of the best bargain signings of the offseason showed plenty of promise during his rookie campaign, particularly with his mobility for a big man and finishing in the pick-and-roll. There were points last year where he looked like a candidate to supplant Baynes as a starting center long term, due to his defensive ability and quickness. He can hold his own against guards on the perimeter and that makes him an ideal fit for Stevens' defensive system. His 3-point shooting (32 percent) was hit or miss, but that's an area to watch this year. If he can bring that up to league average, he may end up playing more than Baynes and should earn himself a nice payday for next summer.

END OF BENCH DEPTH/MAINE RED CLAW: Robert Williams
CONTRACTUAL STATUS: $1.65 million for 2018-19, under rookie contract through 2022
ELIGIBLE FOR FREE AGENCY: Summer of 2022 (assuming Celtics pick up his options for 2020 and 2021)
NOTABLE 2017-18 STATS:  N/A
ASSESSMENT: Barring injuries to his fellow centers, it's hard to envision see the rookie playing meaningful minutes for Boston this year. There's a lot of talent ahead of him in the depth chart and plenty of work that Williams needs to do to refine his offensive game. We'll get a better sense of how far he has to go during preseason action, but his brief stint in summer league showed a guy who struggled to properly set picks and finish with touch on offense. He'll work on those skills, learn the system and get plenty of reps in Maine. Whether or not we see his progress this year at the big league level will depend on injuries.