As 6-10, 240-pound athletes go, Simmons is very fast -- perhaps even elite level -- as a floor sprinter. When playing with guards who can push the pace and pass the way he can, Simmons' effectiveness as a wing finisher will skyrocket. It is easy to get lost in his skill game, but he scores extremely well in just the "raw athlete" category.
Two things jump off the screen when studying Simmons on defense: his incredibly quick hands and his equally impressive lateral foot speed. Simmons finished 32nd in the country in steals per game, and was No. 1 of any player taller than 6-5. His hand speed and overall hand-eye coordination give him an excellent weapon to defend drivers or big men who are not strong with the ball.
Simmons is very nimble and fluid when moving on defense, which hints at great potential on that end at the next level. As the league shifts to more switching on the perimeter, he will be one of the elite few who can not only "hold his own" in space against smaller players, but even excel when isolated -- a potential "defensive player of the year" talent.
Concerns about Simmons?
The knock on Simmons as a shooter is somewhat overrated. Let's not forget that another do-it-all type of NBA star was not a good shooter in college. In two seasons, Kawhi Leonard shot 20.5 percent and 29.1 percent from 3, yet is a career 39-percent shooter in the NBA -- making 44 percent this season.
Simmons has a good-looking stroke, but he never looked as if he was willing to take 3-pointers, and was hesitant to take a lot of jump shots, period. Perhaps this was due to a coaching decision, as he was able to drive by or pass over most defenders. In the NBA, it is fair to expect he will shoot a lot of 3s and be at least good at it, in time.
How good is another matter, a variable that often hinges on who he plays for and who is around him. His growth overall as a shooter will be the single biggest indicator of how special he becomes.
So there's really only one concern scouts could have about Simmons, and it is one that could cost him the top spot in the draft:
How hot is his motor? And how hungry is he to be the best he can be?
Simmons looked bored by season's end, though it would be a mistake to assume he would exhibit the same tendency at the top level of the sport. It remains something to watch closely, but unless Simmons has some serious skeletons in his closet as far as being a teammate or his free-time activities, it should not be much of a concern.
Remember when scouts thought Andrew Wiggins wasn't assertive enough? Wiggins finished seventh this season in free throws attempted (first among small forwards) and scored over 20 points per game as a 21-year-old.
Can he be great?
Simmons reminds me of several players. He has Jason Kidd-like hands on defense, which will be phenomenal for him going against NBA forwards. He's also very versatile like Scottie Pippen, Toni Kukoc and Lamar Odom, who were all very skilled players and excellent ball handlers. I see some Paul Millsap, too -- a chaos creator on defense who is also a highly skilled passer.
Simmons can be a primary ball handler both in the transition game and in half-court sets, where his size-enhanced ability to thread passes both through and around defenders is reminiscent of LeBron (maybe the only real way to compare the two is via their passing/size similarities).
The NBA has plenty of players Simmons' size who can start (and often finish) a fast break from a defensive rebound to a made basket. But Simmons can join the very select few players who can do it on a consistent basis as an ordinary part of his game.
Think about it this way: In 2015-16, only five players at least 6-7 (in shoes) finished in the top 35 in assists per game -- Draymond Green, LeBron James, Nicolas Batum, Kevin Durant and Giannis Antetokounmpo. Four of those guys are max-type players, and Batum could get close to max money this summer. Green, James, Durant and Antetokounmpo also averaged over seven boards per game -- a reasonable expectation for Simmons within a season or two.
Simmons can be one of the top two players on his team in all three phases of the game (scoring, passing, rebounding) while being an elite defender. That puts his ceiling as a perennial All-Star, a max-salary player and, if he learns to be a better primary scorer, a recurrent MVP candidate.