How the Celtics can avoid another Isaiah Thomas situation on defense

Isaiah Thomas’ 2016-17 season remains an incredible anomaly among individual campaigns in NBA history. A 5’9’ former 60th overall pick pumped in nearly 30 points a night on a team with the best record in the Eastern Conference and became a legitimate MVP candidate.

Boston’s offense began and ended with their only perimeter shot creator to the tune of an extra 16.7 points per 100 possessions according to Cleaning the Glass. Unfortunately, Thomas gave back a good chunk of that at the defensive end - an extra 7.6 points per 100 possessions to be exact - and it’s not hard to see why.

As hard as Thomas would try at the defensive end, the limitations of his size were painfully obvious. The smart opponents mercilessly involved him in every set. Screens were used to switch him onto a feared scorer.

“He (Thomas) mostly stays still. It’s not good,” wrote Tim Kawakami, then of The Mercury News. “It’s like he’s not there on most defensive possessions, trying to make himself invisible — in transition, in the half court, whatever the offense is doing, usually Thomas’ defense is not even a minor impediment.”

Those struggles weren’t the sole reason behind the Celtics five-game defeat in the conference finals. Thomas wound up missing Games 3-5 with a hip injury. They did, however, contribute to a hard cap on Boston’s ceiling and were likely the driving factor behind Danny Ainge’s unwillingness to back up the Brinks trucks for a top-five MVP candidate, trading him instead to Cleveland that summer for Kyrie Irving.

Three years later and the Celtics have a similar issue with their latest point guard, Kemba Walker. Though not the singular driving force Thomas was, Kemba has been crucial to Boston’s success all season, specifically with his offensive abilities.

In 1,592 minutes this season, Kemba has the Celtics’ offense humming like the best in the NBA. Their defense has actually remained relatively stout in that time (a 108.5 defensive rating, which would be a top-10 mark) thanks to a stubborn inclination on Walker’s part to do what he can. He’s drawn 18 charges in the regular season, ranking him 7th in the league. But the difference in his absence is too significant to ignore, where a rating of 100.9 would rank first in the league.

Similar to Thomas, Walker suffers from limitations beyond his control. If a mere 6’1’ frame doesn’t already make him the target of every offense possession, it sure will in many forms in the postseason where exploitation is key in a seven-game series.

In a simpler time, Walker’s defensive hindrance could be mitigated simply by having the All-Star guard the opposing team’s weakest perimeter threat. Call it the Stephen Curry philosophy.

Personnel including plus defenders like Marcus Smart and Jaylen Brown make such a tactic possible — like Klay Thompson in Golden State — but teams are much smarter these days. They know how to hunt for the match ups they want, lessening the impact of the other four defenders out there, no matter how stingy they might be.

Countering is part circumstantial and communication, taking into account the abilities and location of the other four players on the court.

In this play from Game 1 of the 2017 Eastern Conference Finals, Thomas unfortunately finds himself in front of LeBron James. Cleveland knew not just how to get the ideal switch, but how to keep it, stationing four shooters around one of the game’s greatest passers to capitalize on any help.

More so, placing three on the weak side all but guarantees a late rotation (at best) James can (and did) take advantage of after easily maneuvering around Thomas.

Any solution that doesn’t involve blatantly abandoning a 3-point shooter has a low chance of success. Given the five-out scheme that’s become the staple of their offense, it’s not difficult to imagine the Milwaukee Bucks running similar sets for a comparable freight train in Giannis Antetokounmpo.

The answer, then, is to dictate who shoots the basketball. Accept that a double team is necessary and that an open shot will be had. Not the easiest strategy to digest but one that, with the proper communication, can have Eric Bledsoe taking the shot instead of Kyle Korver.

Not every lineup employs a similar layout. Some still, believe it or not, place a traditional big man around the restricted area. It’s in those situations where, upon finding a player like Walker out of his defensive element, Brad Stevens can turn to a scramble switch.

The scramble switch is designed to resolve a post mismatch which, in the below example, pits Terry Rozier against Kevin Love. The weak side defender, typically guarding an offensively limited big below the free-throw line, rotates for a switch only as the opposing entry pass is lobbed into the post, detailed from the Celtics’ perspective in the play below from Game 4 of the 2018 Eastern Conference Finals.

This strategy will prove useful against the likes of Joel Embiid, Nikola Vucevic, Domantas Sabonis, Pascal Siakam, Al Horford, and Antetokounmpo. All rank inside the top-20 in post-ups per game for current playoff teams in the Eastern Conference.

Neither Philly, Orlando, nor Indiana has the requisite outside shooting to create a pick-your-poison scenario that combines adequate floor spacing with a respectable post presence. Meaning, your standard help-and-recover should rescue Kemba from being left to guard someone in the post without fear of surrendering the 3-point shot.

Toronto and Milwaukee, on the other hand, rank inside the top-five in 3-pointers made per game. While they lack a traditional inside presence, Miami, who ranks #1 in 3-point percentage, can exploit Kemba’s size with the length and skill of Bam Adebayo or the brute force of Jimmy Butler, as they did against the Knicks in January.

Similar situations against the Antetokounmpos and Siakams of the world are where a plethora of switchable wing defenders will come in Boston’s favor, a lengthy group that can seamlessly rotate between whatever match up lies in front of them.

Though not a post-up, marvel at the multiple efforts given by the Celtics’ defense to secure a stop at such a crucial moment. This is the type of ground they can cover when necessary, such as when their weakest defensive link is left on an island.

If all else fails for Boston, and Walker repeatedly finds himself giving up points at the defensive end, Stevens can always break out a zone defense, of which he’s dabbled with in various forms throughout the season.

In a February road win over the Utah Jazz, Boston ran some variance of a zone defense on 13 possessions — according to YouTuber Drawing the Defense — where the Jazz generated just five points. Kemba was out nursing a knee injury, but the coverage could work to his benefit.

Brad Wanamaker does a superb job in keeping Donovan Mitchell in front of him in the play above, but his efforts were aided by the wall formed by three of his Celtic teammates.

Any zone structure, whether 2-3, 1-3-1, or 2-1-2, could offer Walker similar insurance at the defensive end, where his weaknesses are lessened by the presence of those around him. Confining Kemba to a designated area removes the opposition’s ability to single him out.

“The old theory would be that the zone’s going to give up those (threes),” Stevens said. “Now I think it’s the way you can stay in your general areas and challenge shooters. I understand why people are playing more of it.”

These Celtics have far fewer concerns impeding their way of a potential Finals run than the 2017 team, with more talent on both sides of the ball. That makes taking care of the worries they do have all the more important, expanding a small margin of error against likely challengers, including the only two teams above them in the conference standings.

Walker’s offensive approximation of Boston’s last two point guards has helped keep the Celtics towards the top of the NBA’s hierarchy. Like Thomas, however, the defensive woes that only serve as a minor inconvenience during the regular season, where teams give no more than a night’s thought to their opponent, will be at the forefront of every oppositional gameplan.

“We all just have to really come together and understand that, in order for us to win games, we’re going to have to really play defense,” Kemba explained days before the season.

Understanding and actually doing are two different things. Walker has proven far more willing and engaged than Thomas ever did. There will come a point, though, when that will only give Boston so much upon being run through countless switches.

It’s in those moments where a top-five defense will have to do a bit more heavy lifting to cover what defensive woes lie out in the open. In some form or another, it’s the only way a championship can be remotely within reach.