PHILADELPHIA, PA - OCTOBER 23: Al Horford #42 of the Philadelphia 76ers handles the ball against Daniel Theis #27 of the Boston Celtics on October 23, 2019 at the Wells Fargo Center in Philadelphia, Pennsylvania NOTE TO USER: User expressly acknowledges and agrees that, by downloading and/or using this Photograph, user is consenting to the terms and conditions of the Getty Images License Agreement. Mandatory Copyright Notice: Copyright 2019 NBAE (Photo by Jesse D. Garrabrant/NBAE via Getty Images)

This past offseason, Al Horford left the Boston Celtics for the Philadelphia 76ers in free agency. Many analysts and experts considered the Celtics doomed, as Horford was a key part on both offense and defense. Yet, the Celtics find themselves with the best record in the league at 10-1. How are they doing it?

This year, the Boston Celtics have the 12th best defensive rating in the league (104.7), even while giving up 133 points to the Wizards Wednesday night. They also support the 5th lowest opponent’s field goal percentage (42.8%), and the 9th lowest opponent’s three point percentage (33.3%).

Last year, Boston finished with a 107 defensive rating, two points worse than this year. They also had an opponent’s field goal percentage of 44.8 and a 3 point percentage of 34.4, both worse numbers than what they currently have.

It’s safe to say the Boston Celtics defense so far this year has been a surprising bright spot without All-Star big-man Al Horford. To put Horford’s defensive excellence in perspective, in the 2017-2018 season, Horford finished fifth in voting for defensive player of the year, only behind Rudy Gobert, Joel Embiid, Anthony Davis, and Paul George.

On the offensive side of the ball, the Celtics have the best offensive rating in the league (113.8), compared to a 111.3 rating last year. So far, it would appear they haven’t missed Big Al one bit.

In place of Horford, the center position has been filled by a variety of players, including Daniel Theis, Robert Williams, Enes Kanter, Grant Williams, Vincent Poirer, and more — Tacko Fall?!

Theis has been the main center for Boston, starting seven of the eight games he has been available for. He is averaging a stat line of 6.1 points, 6.4 rebounds, 1.3 assists and 2.1 blocks, all career highs. Theis has proven to be a solid offensive player and rebounder, while protecting the rim at quite an impressive rate — ranked seventh best in the league for blocks-per-game.

In his second year, Robert Williams is averaging 5.9 points, 4.9 rebounds, 1.9 assists, and 1.6 blocks for the Boston Celtics. Along with absurd athleticism in finishing alley-oops, he has continued his defensive prowess that he showed in his rookie year. If he can continue his absurd 78% shooting from the field, the Celtics will indefinitely be able to continue relying on him as an offensive option

Grant Williams has shown himself as an option as a small-ball center. Poirer has seen limited minutes, but he has looked like an effective, rim-running seven footer — something that the Celtics have lacked in past years. Look for him to develop to make a bigger impact later in the season.

Enes Kanter hasn’t gotten into game form yet, as he got injured on the first game of the season, but he should be a productive option on the second-unit to get quick points. With Boston’s underwhelming offensive output from the second unit so far, Kanter will be useful to give them a jolt, something he’s proven capable of throughout the years.

Besides the big men positions, the young Boston Celtics wings (Jayson Tatum and Jaylen Brown) have taken a step forward in their progression this season, averaging a combined 39.9 points per game, compared to 28.7 points last year. Before the season, everyone was looking to Brown and Tatum to carry the offense with the loss of Horford and Kyrie Irving, and so far they’re doing it.

Finally, with Kemba Walker replacing Irving, it’s clear the ball is moving at a much more rapid pace. The team atmosphere has been much improved, and that improvement can be attributed to Walker (along with the departure of Irving). The movement of the ball is making this team fun again, even without the veteran presence of Al Horford.