The Celtics Are Just Dress Rehearsal for a Cavs–Warriors Finals

The NBA's Eastern Conference Finals begin tonight, and while Boston holds home-court advantage, there is a pretty good chance that the top-seeded Celtics will be as overmatched as Cleveland's previous two playoff opponents.

The Cavaliers are a tough matchup for the Celtics. The defending league champions won three of their four games against Boston during the regular season, including, most notably, a 23-point statement win in April.

Like many teams, the Celtics lack an on-ball defender who is big, strong, and quick enough (sorry, Jae Crowder) to slow LeBron James, who averaged roughly 29 points, nine assists, and nine rebounds per game against Boston this season.

The Celtics also like to play small: their most-used playoff lineup features Crowder at power forward alongside three guards, Isaiah Thomas, Avery Bradley, and Marcus Smart. Problem is, small lineups play right into Cleveland's hands, allowing coach Tyronn Lue to spread the floor and surround James with four elite three-point shooters. In the regular season, the Cavs had a 133.1 offensive rating (ORTG) against Boston when four perimeter players flanked James.

Oh, and remember that off-the-backboard alley-oop Cleveland pulled off in the opening moments of its second-round sweep of Toronto? The Cavaliers did the same thing against the Celtics back in November.

Boston will get creative, and Brad Stevens is one of the best coaches in the league at making unexpected tweaks to his rotation, or confusing opponents with defensive schemes. Ultimately, though, the Celtics just aren't very strong in the areas that would make the Cavs uncomfortable.

A NBA Finals rubber match between Cleveland and Golden State seems likely. The Cavs' series against Boston may not be particularly competitive, but it will be a final dress rehearsal for a team that entered the playoffs with major defensive issues and still appears to be in the process of flipping on its postseason switch.

What can James and company do against the Celtics to prepare for the Warriors? Let's take a closer look.

Kyrie Irving has been in a playoff slump. Through the first two rounds, he's shooting just 39.9 percent from the field and 28 percent from behind the arc; both numbers are down over 8 percent from his regular-season averages. He has only enjoyed one breakout game so far, a 37-point outburst against Indiana in the first round.

Irving has finished with a positive plus-minus rating in all eight of Cleveland's playoff games, but those numbers remain ominous. The Cavs will have to lean on him against both the Celtics and the Warriors, and in ways they've so far been able to avoid to this point.

Like the Warriors, the Celtics rely heavily on an undersized, defensively challenged point guard to close out games. While Isaiah Thomas led the NBA in fourth-quarter scoring during the regular season, the Celtics know that he's a target for isolations and pick-and-rolls on the defensive end. This is where Irving can feast. The Cavaliers will work to get Thomas matched up against him, and let him go to work scoring, drawing fouls, and generally wearing Thomas out.

It's a perfect primer for Golden State. In last year's Finals, Irving shot nearly 47 percent from the field, over 40 percent from behind the arc, and was especially effective when targeting Steph Curry in the series' final three games. His go-ahead shot in Game 7 remains etched into the minds of Warriors fans, as does his 41-point explosion in Game 5. Cleveland needs Irving at his best against Golden State, and Thomas is an ideal defender for rediscovering his groove.

During the regular season, the Celtics attempted and made more three-pointers than the Warriors. Really. Boston is hardly shy about letting it fly, and like Golden State, the Celtics like to play through pick-and-rolls by allowing their center to make reads on rolls and dribble handoffs. And while the Celtics led the NBA in handoffs, whereas the Warriors use off-ball screens more than any other team, both actions require similar defensive focus.

They also require switching screens. With the Celtics preferring to play small, the Cavaliers should be able to get away with switching across the board most of the time. Al Horford isn't enough of a threat to worry about mismatches inside, and while Thomas is quick and crafty, the Cavaliers should be able to make him work on switches rather than try to fight through every handoff. All of this will be great practice for the Warriors, who basically force opponents to switch defensively through frenetic screening and cutting.

Cleveland brought a 108.0 defensive rating (DRTG) into the playoffs, good for No. 22 in the league. That number rose to 111.1 against Indiana—not great!—but against the Raptors, the Cavaliers tightened up and posted a 100.9 mark. Considering that Toronto had the NBA's sixth-best offensive rating during the regular season, it was an impressive turnaround.

That said, four games of locked-in defense probably isn't enough preparation for the Warriors—so another four games (or more) of tough defense against a Celtics team that loves to spread the floor and shoot threes could go a long way.

For all of Golden State's talent and brilliance, their biggest vulnerability is on the defensive glass. Boston shares that weakness, as the Warriors and the Celtics ranked No. 27 and No. 28 in defensive rebound percentage and opponent second-chance points. Against both teams, Cleveland's Kevin Love and Tristan Thompson will have the opportunity to eat.

Love showed renewed aptitude on the offensive glass this season, grabbing more offensive boards per 100 possessions than in either of his previous two years on Cleveland. His revival actually began in Game 7 of last year's Finals, when he grabbed four huge offensive boards after managing just four total in the previous six games. Impressively, Love has managed to increase his three-point attempt rate this season, as well. That ability to space the floor and crash the glass will be important against Boston and Golden State.

So far in the playoffs, Love has grabbed just nine offensive boards in eight games. That isn't a complete shock; Indiana and Toronto favored bigger lineups. That will flip against the Celtics and the Warriors, and it will be imperative for Love to dominate the boards whenever he is matched up with an undersized power forward.

Meanwhile, Horford is susceptible to giving up rebounds when faced with a tenacious and physical opponent. Thompson fits the bill, and will make him work.

The Cavaliers are peaking at the right time. While it's important to work on the areas they need to improve in order to compete with the Warriors, they don't need to abandon what's already working. Through the first two rounds, Cleveland has all but perfected its spread offense, and James looks as fresh and confident as ever. That same style worked well against Boston all season, as the Celtics just don't have the length to cover four shooters and James. Just look at how effortless things can appear for the Cavs.

If Cleveland can maintain the defensive effort and execution it showed against Toronto, add rebounding, guard the three-point line, and get Irving going, then the Eastern finals could be a sweep. And if that happens, the Cavs will enter the Finals brimming with confidence, knowing that they are as prepared as possible for by far their toughest task yet.

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