I would love to land Marc Gasol in free agency this year. Oh sweet goodness, that would be wonderful, he could run some offense out of the post, with quick and accurate passing to shooters on the perimeter. More importantly, he would protect the rim.

I would also love to land Deandre Jordan in free agency this year. I can picture the pick and rolls with Isaiah Thomas, and it puts butterflies in my stomach. More importantly, he would protect the rim.

Unfortunately, it is not very likely that we land either of these players in free agency, or any other big-name free agent big men. However, there are a lot of centers who will be free to move to a different organization during this summer, and are capable of providing the defensive presence in the paint that the Celtics have been missing since the departure of Kevin Garnett.

Alexis Ajinca is a 27-year-old Frenchman who has spent 6 seasons in the NBA (he took a brief hiatus from 2011-2013, to attempt to play overseas). He has spent the past two seasons playing center for the Pelicans, logging occasional starts and demonstrating notable improvement on both ends of the floor. He received a salary of $981,084 in 2014-'15, so will likely neither expect nor command a huge contract.

The Pros:

The first positive with Ajinca is his size. The Frenchman stands 7'1" tall, with a massive 7'9" wingspan, according to DraftExpress. He has bulked up considerably since entering the league, and now weighs almost 250 lbs. Ajinca uses his size effectively on both sides of the court, scoring efficiently out to 16 feet, and functioning as a steady rim protector.

In 14.1 minutes per game this past season, Ajinca averaged 6.5 points, 4.6 rebounds, .7 assists, and .8 blocks on 55% shooting from the floor. While those raw numbers are hardly eye-popping, his per-36 minute numbers of 16.7 points, 11.8 rebounds, 1.8 assists, and 1.9 blocks paint him in a significantly more favorable light, as does his PER of 19.9. While it seems unlikely that he would retain such efficiency and effectiveness with more minutes, he is definitely a rim protector that could give the Celtics the defensive they need. 82games.com awarded Ajinca a block rating of 8.2, which certainly compares favorably to Tyler Zeller's score of 3.5.

Furthermore, Ajinca could be a minimal financial risk. He was labelled a bust after playing poorly in his first stint in the league, and was picked up by the Pelicans on a very small contract. He might be had this off-season without too much of a financial commitment from the Celtics. The importance of the projected size of his contract cannot be overstated, given the Celtics' well-known desire to land a big-name free agent this off-season.

The Cons:

Ajinca only played 14.1 minutes per game for the Pelicans last season, and logged an average of 3 minutes per game in the Pels' playoff series against the Warriors. While this is anecdotal evidence, it does reveal an important fact about the big man; he is slow-footed, and doesn't match up well against the increasingly prevalent focus on small ball and outside shooting.

Ajinca's success came in very limited minutes, so a direct per-36 extrapolation is unreasonable. Analytically, Ajinca could be very successful with more minutes, but he would be far less successful in longer stretches against quicker opposition. He has not yet proven that he has the potential to be a good starting center, or a starting center at all. Picking up Ajinca on even a medium-sized contract would certainly be a gamble.

By The Numbers (This season):

Block Percentage: 4.0%

Total Rebound Percentage: 18.7%

Opponent FG Percentage at the Rim: 52.3%

Blocks per 36 minutes: 1.8

PER: 19.9

Opponent PER (per 48 minutes): 16.7

Ed Davis is a 6'10" center/power forward, who is currently under contract with the Lakers (player option). He is a 5-year NBA veteran out of UNC, and turns 26 in just a couple of days. He has played consistently for the Lakers, moving into and out of the starting lineup, and playing 23.3 minutes per game. Davis has a player option for this coming year, so while he is not technically a free agent, he may be available to sign during the off-season.

This past season, Davis averaged 8.3 points, 7.6 rebounds, and 1.2 blocks per game on 60.1% shooting. He played 23.3 minutes per game for a Lakers team that was in a down year. He was the only player on the roster that could both effectively protect the rim and shoot efficiently (20.0 PER). He has a player option for this coming year, so while he is not technically a free agent, he may be available to sign during this off-season.

The Pros:

This past season, Davis averaged 8.3 points, 7.6 rebounds, and 1.2 blocks per game on 60.1% shooting for a Lakers team that was in a down year. He was the only player on the roster that could both effectively protect the rim and shoot efficiently, and was a bright spot for a team lacking in talent.

First of all, Davis projects as a quality rim-protector. His blocks per minute extrapolate out to 1.9 per 36 minutes, which is certainly significant. This season, he had a block rating of 8.1, according to 82games.com, and a block percentage of 4.3.

Additionally, Davis is a solid rebounder. He has a rebounding percentage of 18%, pulling down 11.7 per 36 minutes. Perhaps even more exciting, Davis notched 2.9 offensive rebounds per game. Celtics fans will surely be able to appreciate the value of offensive boards after getting gashed by Tristan Thomson in the playoffs this year (seriously, that guy killed us on the glass).

His efficient shooting is also valuable. Davis shot 60% from the floor, with 96.1% of his shots coming from within 10 feet. He understands his role, sticking around the basket and finishing consistently.

The Cons:

Davis does not have enough size to play center against many of the bigger 5s in the league. He stands 6'9.75" (in shoes), with a 7' wingspan. He is athletic enough to make up for many of the issues created by his height, but he likely does not have the mass and strength (227 lbs.) to bang with the big boys down low. This shows up in the PERs posted by his opponents. He is holding power forwards to a PER of 20.0 per 48 minutes, but allows centers to post a PER of 21.8, according to 82games.com.

Additionally, he does not have much of an outside shot, so may not fit in well with Stevens's pace and space offense. This past season, he only shot 35.3% from outside of 10 feet. His need to stay around the basket on offense could gum up slashing lanes for Avery Bradley and Jae Crowder, or driving lanes for Isaiah Thomas.

By The Numbers (This Season):

Block Percentage: 4.3%

Total Rebound Percentage: 18.0%

Opponent FG Percentage at the Rim: 53.9%

Blocks per 36 minutes: 1.9

PER: 20.0

Opponent PER (at center, per 48 minutes): 19.8

Koufos is perhaps the most well-known player on this list. He has been a successful backup to Marc Gasol in Memphis for the past two years, and was a starting center in Denver before that. It has been reported by various sites that he could be targeted by the Celtics this off-season, and he would certainly fill some needs for the team.

He is a 7-year NBA veteran, and is still just 26 years old. His salary last year for the Grizzlies was $3M, and he will be looking for a raise as a free-agent this off-season.

The Pros:

The first positive aspect of Koufos' game is his defense. Koufos held opposing centers to a PER of 15.3 this past season, and blocked 1.7 shots per 36 minutes. That second figure is somewhat misleading, because Koufos is more of a straight-up defender, altering more shots than he blocked. This year, Koufos held opposing players to a shooting percentage of 46.9% at the rim. This figure legitimizes Koufos's case as a legitimate starting-caliber rim-protector.

His rebounding is also very strong. Koufos pulled down 5.3 rebounds per game this season, at a rate of 11.4 per 36 minutes. This figure has remained consistent; over the past 4 years, and regardless of playing time, Koufos has averaged over 11 rebounds per 36 minutes (5 years ago, he averaged 10.8). The big Greek will certainly help Boston's poor rebounding (Boston ranked 20th in rebounding differential this past season).

Finally, and perhaps most importantly, Koufos has a lot of experience as a starter. Over the past four years, he has started in 130 NBA games, and has been successful as a defensive center. Signing Koufos doesn't project to be very much of a gamble (unless the contract is enormous), which is a huge positive. That's not something that can be said about the other two prospects discussed here, and its value cannot be overstated.

The Cons:

Koufos did not have a very efficient offensive season last year. He finished with a PER of 14.2, which is below league average. He shot 50.8% from the floor on the year, which is certainly lower than optimal for a center. His performance from the line was not great, either. He shot 64.7% from the stripe, which is better than Deandre Jordan, but certainly not good. What's more, he only shot 33.3% from the floor outside of 10 feet, indicating that he has little to no value as a floor spacer in Boston's pace and space offense.

Despite his apparent offensive limitations, Koufos will certainly be a highly sought-after free agent during this off-season. His experience and success as a rim-protector make him desirable, which means other teams will be bidding for his services as well. The Celtics will have to spend much more money to sign him than they would have to spend on either of the other two players discussed here. This means that while Koufos isn't much of a gamble from an on-the-court perspective, he represents a larger gamble from a financial perspective. Of course, this will be mitigated by the massive projected salary cap looming in the near future.

By The Numbers (This Season):

Block Percentage: 3.9%

Total Rebound Percentage: 18.1%

Opponent FG Percentage at the Rim: 46.9%

Blocks per 36 minutes: 1.7

PER: 14.2

Opponent PER (at center, per 48 minutes): 15.3

Final Thoughts

All three of these players could provide the rim protection that Celtics fans have been absolutely clamoring for for the past couple of seasons. As a team, Boston has not done an adequate job of defending the paint. That could change this upcoming free agency, with the signing of a player that may not be on everyone's radar.

Ajinca could prove to have a game as giant as he is, if given extended minutes.

Davis could prove that he has the athleticism to make up for his size, and be a small-ball rim protector for the Celtics.

Koufos (who almost didn't make this list, due to his presence on several teams' free-agent wish lists) could prove that he truly does deserve the money and the permanent starting job that he's been craving all along.

There is one more thing to consider; one thing that we often forget, in our rush to identify a 'missing piece' on a team, is the importance of raw talent. While Zeller is no rim-protector, he spent the past season proving that he is definitely talented. When we consider the free-agents we could acquire this off-season, we must continue to ask ourselves if adding that 'missing piece' is worth sacrificing the presence, or playing time, of the pieces we already have.

So, what do you think; could one of these lesser-known players grow into our defensive-anchoring center of the future?

All stats from Nba.com, basketball-reference.com, espn.com, and 82games.com