During the 13-4 stretch the Celtics had before the All-Star break, Kelly Olynyk was averaging a modest 12 points and 4 rebounds over 20 minutes a game, but those numbers don't tell the entire story. KO has been an analytics darling during his entire three-year career in Boston, and this season has been no different. In those seventeen games, Olynyk lead the team in +/- at +8.5. He was shooting a very efficient 49% but leading the team in eFG% at 57.7% because of his 41.3% clip from behind the arc. Olynyk also had a higher usage rate than Evan Turner, Marcus Smart, Avery Bradley, Jae Crowder, and Amir Johnson, all of whom averaged more playing time.

Olynyk might seem like some strange statistical anomaly. He's not the most athletic player on the floor, and on defense, he doesn't provide the stout rim protection expected from a traditional big man. However, his all around skill set and high IQ make him a crucial cog in Brad Stevens' read-and-react system.

With David Lee now bought out, Tyler Zeller looks to be the natural beneficiary of Olynyk's three week absence. The Celtics have been very good at relying on the next man up, but unfortunately, Zeller just isn't the same player as KO. Even though he's come on of late, Zeller is a finisher, specifically off the pick-and-roll and around the rim. Olynyk, on the other hand, can score from anywhere on the floor and can be an above-average playmaker off the dribble. Ultimately, so much of it is about spacing. Check out these two sets from Friday's blowout loss in Utah:

Rudy Gobert was a problem for Boston all night, and because Zeller is a natural roll man off the PnR, Gobert was constantly in the paint. Zeller sets a good pick for Thomas, but because TZ rolls (and doesn't pop to the three point line like Olynyk could), Thomas is dissuaded from driving, and the paint is clogged for Sullinger's dribble drive.

Zeller initially sets a pick for Smart, but Marcus swings the ball to Jonas Jerebko, and it eventually leads to a pick-and-roll with Evan Turner going to the rim. The problem is, Zeller has already brought Gobert into the paint, allowing him to help on Turner's floater. He commits a shooting foul, but you can see how the spacing is affected without a floor stretching big.

Zeller is a fine replacement as the fourth big, but it's going to have an effect on the rest of the players. Driving lanes for Smart and Turner won't be as open, and that might limit the amounts of kick-outs for threes. Olynyk was such a linchpin of how the Celtics like to play. Thankfully, the Celtics only play 10 games over the next 23 days with 7 of them at home. Unfortunately, most of the teams Boston will face have big front lines where Olynyk's spacing could help.