Willie Cauley-Stein is the rim protector the Boston Celtics are looking for

The Boston Celtics have significantly improved on defense this season due to the efforts of Jae Crowder, Jonas Jerebko, Marcus Smart, and Tyler Zeller. But the roster still lacks a dominant shot blocker that can protect the rim from demonic forces. It's easier said than done to find the perfect man for that job, but Kentucky big man Willie Cauley-Stein could be Boston's primary target this summer.

The 21-year-old Cauley-Stein has the tools to become an elite rim protector. As covered on SB Nation, the 7-footer is one of the most athletic and versatile big men you'll ever watch; at the Kentucky Combine he posted exceptional scores in speed drills and his long wingspan gives him the ability to block shots from anywhere.

What the Celtics need is an eraser -- a player who can expunge the mistakes of his teammates, whether it's with a breathtaking block or simply a contested shot. No team defense or individual defender is perfect, so it's crucial to not let mistakes accumulate over the course of a game.

Cauley-Stein did that countless time this season by stifling the opponent's best player, which led the Wildcats to have arguably the best defense in the history of college basketball.

But blunders still happen even for the best defenses. On this possession both he and his teammates lazily jog back on defense after a made basket, which gave Arkansas an open layup opportunity.

Except few layups are truly open when WCS is on the court and the play resulted in a block. This is the definition of what it means to erase mistakes and the Celtics need this type of talent if they make the jump to having an elite defense over the next few years.

With an outstanding vertical leap and elastic wingspan, Cauley-Stein will undoubtedly see this skill translate to the next level, which is why he's currently ranked sixth on my big board.

Bill Simmons suggested on a recent podcast of Bill Don't Lie that the Celtics had interest in Cauley-Stein before he withdrew from last year's draft.

"I think if the Celtics had promised [Cauley-Stein] they would have taken him at 17 he would have come out last year," Simmons said. "From what I heard. Word on the street. Word on the street."

Danny Ainge admitted last season that he felt rim protection was a primary team weakness, so they drafted Smart and traded for Zeller, but neither of them can padlock the paint like Cauley-Stein can.

The Kentucky big man would've been in range for the Celtics to draft at 17 last year, but one year later he is locked in as a top 10 pick. Boston will have a draft pick in the 9 to 16 range, depending on if they make the playoffs or not, so they'd probably have to trade up for him.

But they have trading versatility, with four selections in the top 45 (two firsts and two seconds), a plethora of future picks, and tradable young players. It's not inconceivable for the Celtics to trade up into the 5 to 8 range of the draft to snatch the prospect they're targeting.

In the clip above Cauley-Stein shows on the side pick-and-roll and contains the ball handler until his teammate recovers, but that left his own assignment wide-open for a high percentage corner three. But WCS managed to sprint from the middle of the free throw line all the way to the corner to make a strong contest to influence a miss.

This play won't show up in the box score, but it's a prime example of his potential as a pick-and-roll defender. With so many teams spreading the floor with stretch forwards, Cauley-Stein's extraordinary perimeter defense makes for a perfect fit to neutralize the pick-and-pop attack. The Celtics are one of the most switch-heavy teams in the league, so Cauley-Stein also presents value in his ability to play man-to-man against smaller players.

Detractors will point to Cauley-Stein's offense as a wart, but those criticisms are unwarranted when considering how he'll be used in an NBA offense.

Cauley-Stein will almost never be asked to post up or shoot the ball, but he'll be required to roll hard to the rim in the pick-and-roll and transition, and clean up inside via offensive rebounds and dump offs. Fortunately, WCS already excels in those areas.

Watch that thunderous slam and now imagine Cauley-Stein rumbling down the middle of the floor after a high pick-and-roll with Isaiah Thomas at point guard. Most of Cauley-Stein's dunks came on alley-oops or in transition, like the one above, but NBA spacing will provide him more opportunity to a larger complementary impact in the half court, much like DeAndre Jordan or Tyson Chandler.

Cauley-Stein's more worrisome flaws are his defensive rebounding and passing, but his discipline and focus on defense have both progressed, which was a chief concern after last season. WCS also must improve as a screen setter, but that is the case for nearly every big man entering the next level.

If the Celtics have their eyes set on adding a rim protector from the draft, Cauley-Stein won't be their only option. Kristaps Porzingis, Myles Turner, and Jakob Poeltl will all be available in the lottery to mid-first and could also be targets. Porzingis and Turner present better tools as floor spacers, but neither of them are as close to ready to make an impact like Cauley-Stein.

No matter the case, the Boston Celtics will have options as they approach the offseason, and it wouldn't be too surprising if Willie Cauley-Stein is at the top of their list to fill the rim protector role.

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