Williams was seen by most as a potential lottery pick (top 14). who might slip into the late teens.
MORE ON WILLIAMS - C's take advantage of Texas A&M big man slipping to 27th
But all the way to 27?
To have such a precipitous fall, there are likely factors weighed by NBA teams that passed on him that go beyond his ability.
Of greater concern for the Celtics, is how good can he be in Boston?
As far as the floor for him as a player, you can go in a lot of directions, from Stromile Swift, who was one of the bigger draft busts in recent memory, to former Celtic Amir Johnson, who has been a solid-but-not-spectacular pro for more than a decade.
In looking at current NBA players who seem very similar to where Williams is now, Houston's Clint Capela in many ways mirrored the promise and potential problems that many see in the 6-foot-10, 241-pound Williams.
Here's a look at five traits that give the Celtics reason to be cautiously optimistic that they may have landed this draft's version of Capela:
Late first-round picks
Clint Capela was considered one of the best athletes to ever come to the NBA, from Europe. Despite some impressive physical traits, he slid down the board before ultimately landing with the Houston Rockets, who selected him with the 25th pick in 2014. Williams is talked about in a similar vein when it comes to having elite athleticism. And, like Capela, he, too, saw his stock take a draft-night dip to where he was finally scooped up by the Celtics at 27.
The term "rim-runners" is relatively new to the basketball lexicon, but it has been around for a while and it really does matter. Players who can run the floor effectively not only create shot attempts for themselves, but also puts stress on a defense that allows the teammates of elite rim-runners to get great looks at the basket. As talented as James Harden and Chris Paul are, they benefit from Capela's ability to get up court in a hurry. Williams has a similar skill to his game, but wasn't surrounded by the type of quality shooters to which that strength of running the floor was on display enough. In Boston, he'll make the guys around him better offensively by doing what he does best and that's run the floor and, when given the opportunity, play above the rim.
Since coming into the NBA, Capela has been a stabilizing force for a Houston team that has steadily improved collectively on defense. He has great timing, above-average length, and instincts at that end of the floor that has served him well. His 1.9 blocks per game last season ranked fourth in the NBA. Williams comes into the NBA with similar potential at that end of the floor. In both his seasons at Texas A&M, Williams was named SEC Defensive Player of the Year. In addition, he led the SEC in rebounds (9.2) and was second in blocked shots (2.6 per game), despite playing just 25.6 minutes per game.
Bad free-throw shooters
When you fall as far in the first round as Capela and Williams, you know there are some warts to their overall game. The one thing both share unequivocally is a knack for not making free throws. Capela is a career 48.2 percent shooter from the free-throw line, but the good news for Rockets fans is he made a career-best 56 percent last season and has actually improved from the line every year he has been in the NBA. Williams has been just as woeful from the line. In his two seasons at Texas A&M, he shot 54.1 percent from the line, but that included last season when he connected on just 47.1 percent of his free throws.
Established, successful franchises
When the Rockets drafted Capela, they were coming off a 54-win season with a roster that included Harden, Chandler Parsons (when he was healthy), Dwight Howard and Jeremy Lin (who like Parsons, was healthy then). So, he knew early on that by playing to his strengths – rebounding, defense, running the floor – he would be a contributor in a year or two. Williams is walking into a similar situation. Boston has established veterans ahead of him in the frontcourt, but the strengths of his game – rebounding, defense and running the floor – provides an element that Boston won't get from anyone else. And by playing to his strengths, he'll only enhance the success of a team that has already built to contend for an NBA title this season.
MORE NBA DRAFT - DJ BEAN on the winners and losers Thursday night