A year ago, the Celtics had about 28 feet worth of centers on their roster. This year they don’t even have more than one O’Neal and everyone is worried about their lack of size as the season approaches. Everyone, that is, except coach Doc Rivers.

“I don’t think the league’s that big,” Rivers said before the team hit the practice floor on Thursday at TD Garden. “It’s not a big concern for me. I would love to have [size]. I’d rather have a better player than a taller player.”

Given a choice, Rivers continued, “I’d rather have the skill. If I’m going to have a bad five or a skilled four, I’m taking the skilled four and we’ll make it work.”

The Celtics added two new frontcourt players in Brandon Bass and Chris Wilcox and neither is a center by trade, leaving just one true center on the roster in 33-year old Jermaine O’Neal who has a long history of injury problems. What the Celtics lack in height, they hope to make up for in versatility.

Here’s where we get to David West, whose addition would have been perfect for this plan because he would have not only given the Celtics another excellent shooting big man, he also has a varied offensive game including a much-needed ability to score in the post. But West signed with the Pacers, leaving Rivers with a thin frontcourt that is just one injury away from trouble.

Acquiring West’s was team president Danny Ainge’s best shot in a league where Kwame Brown got a $7 million contract from Golden State. There simply aren’t that many options for a team that is capped out and had so many roster spots to fill with the understandable goal of keeping the financial books clean for the summer of 2012. “We’d like somebody that can play and is big,” Ainge said. 

So, Rivers will go with what he has and their big man rotation at the moment is Bass, Wilcox, O’Neal and Kevin Garnett, who will also see time at the center position. Garnett and Wilcox have the size and length to guard centers and Bass has the strength. In fact, the 6-foot-8 Bass may be the team’s nominal backup center.

Rivers said earlier in the week that if he has Bass and Wilcox on the floor together then Bass would probably draw the center matchup. He also likes the combination of Bass and Garnett. “That will be a lineup you’ll see a lot,” he said. “I like that lineup because they both spread the floor and they’re both hard to guard.”

Garnett is the key. He will play his 30 minutes a night and between O’Neal, Wilcox and Bass will divide up the other 66 frontcourt minutes depending on the matchups. In reality, declaring one player a four and the other a five isn’t that important. Look around the league. The dominant center belongs to a different era. Using HoopData as a guide, there were just a dozen players classified as centers who saw more than 30 minutes per game last season.

Dwight Howard is obviously the league’s most dominant big man and he will be a major problem for the Celtics, just like he is for every other team. Howard is the reason they stocked up on centers the last few years, but he’s also just one man and the Celtics have shifted their attention to teams like Miami who had a serious matchup advantage up front during last year’s playoffs.

Here’s the list:

True centers: Howard, Andrew Bogut, Brook Lopez, Marc Gasol, Nene.

Big power forwards: Al Horford, Al Jefferson, Emeka Okafor, David Lee, Joakim Noah.

Bargnanis: Andrea Bargnani, Channing Frye.

You’ll notice there are some other names missing. Players like Tyson Chandler, Andrew Bynum, DeAndre Jordan, Roy Hibbert, Chris Kaman, Marcin Gortat and, of course, Kendrick Perkins. They all clock in between 25-30 minutes a night and while some are more skilled offensively than others, none of them are their team’s focal points.

“If we have enough fours who can play both and we have enough fouls we can get away with it,” Rivers said.

Rivers praised Greg Stiemsma, a veteran of the D-League and several overseas journeys, after Thursday’s practice and the Celtics like his toughness and ability to block shots. If they don’t make another move, he may have a chance to stick, but the Celtics main problem is simply a lack of depth. O’Neal and Garnett have both had significant injury issues in the past and losing one for any length of time would be difficult. Losing two would be a disaster.

If you can’t match height vertically, the next best option is stretching the court horizontally. The Celtics needed two things to remake their frontline: shooting and athleticism and Bass and Wilcox are expected to provide both. (Rookie JaJuan Johnson may fit into this mix, as well. He’s not a banger but he can shoot and Rivers has been impressed by his athletic ability. He’s also, obviously, a rookie).

The Celtics were among the league's top shooting teams last season, but that was mainly due to standout seasons from Paul Pierce and Ray Allen. No one is expecting Pierce or Allen's production to tumble dramatically, but it's not wise to have to rely on them to duplicate such excellence, either. Even with their shooting prowess, the Celtics offense ranked below league average in efficiency owing to a terrible turnover rate, an ineffective bench, almost zero post-up game (again, West would have been invaluable in that regard) and an inability/reluctance to work the offensive glass.

Wilcox shot 58 percent last season and does most of his work around the basket where he converted 70 percent of his shots at the rim, one of the higher marks in the league among big forwards. He’s not an elite offensive rebounder, but he’s not far off and the Celtics ranked dead last in offensive rebounding rate by a wide margin.

“Most of the time fours and five are switching anyway so there’s not really not that much of a difference,” Wilcox said. “Everybody’s got something different to their game so if you bring something different to the table you might have something that the other man doesn’t.” 

What Wilcox brings is energy and athleticism. His best years came with Seattle from 2006-2008 when he averaged 13 points and seven rebounds, but his career hit a roadblock after the team moved to Oklahoma City.

He was traded to New York where he saw limited playing time and then moved to Detroit where minutes were also scarce. Wilcox turned it on in the final month of the season, scoring double figures in 11 of the final 16 games and posting his best season statistically since his glory days as a Sonic. The key, as it’s been throughout his career, is tapping into that potential.

“We’ve got to get something out of Chris,” Rivers said. “I think he can really play. I don’t think he’s ever really had to play. He’s never been in the playoffs. If we can get him to have a mind change, he can be good for us.”

Bass is exactly the opposite. He generated 70 percent of his offense on jump shots, hitting 47 percent of his attempts from 16-23 feet, ranking alongside players like Garnett and West, and he is also strong and athletic enough to finish inside.

“I like that he can score, number one, before anything else,” Rivers said. “Great pick and pop player. Not bad in ISO situations away from the basket. We need that coming off the bench. I like that he just plays hard. Low maintenance, just plays hard, and that’s something we were looking at.”

The Celtics need their new frontcourt rotation to stay healthy and productive, two areas that were a major concern for the entire second unit last season, but particularly up front. With the exception of Glen Davis, who played both frontcourt positions, Rivers was limited in what he could use around Garnett. His centers were almost always injured and with Garnett playing 30-32 minutes a night there was no depth at the big forward position, leaving Davis often overextended and overworked.

The same held true for the four All-Stars. There were too many nights when Pierce, Allen and Rajon Rondo had to play big minutes and just as importantly, too many times when they and Garnett built leads that were wasted by an ineffective bench.

Of the Celtics 10 most productive lineups last season, six featured all four of their All-Stars and nine had at least three of them on the floor, per Basketball Value. Conversely, they struggled mightily whenever there were less than two of them playing at the same time. 

“This year I’m hoping that [we can use] one at most at times,” Rivers said. “If we can get away with one of them on the floor and still play well, that’s huge.”

It’s huge because the Celtics will play 66 games in 124 days. They’re no different from anyone else in that regard, but Rivers can’t afford to burn his star players out in March if they’re going to have any chance in May. Bass, Wilcox and Johnson are younger, more versatile, more athletic and more skilled offensively than what the Rivers had to work with last season and at the very least that is a positive development.