CHICAGO -- Celtics point guard Rajon Rondo admirably pinned Boston's offensive struggles during Saturday's loss to the Chicago Bulls on himself, noting after the game that it is his job to quarterback the team, and as such, any offensive turbulence falls on him.
But on a night when coach Doc Rivers suggested that Boston basically "bounced the life out of the game," it was painfully obvious that a heavy-legged Celtics squad playing its fifth game in seven days and the back end of its second back-to-back of a grueling week didn't have the energy to do the little things that have made Boston the best shooting team in the league.
And it started with a lack of screens.
The Celtics hit the floor hell-bent on getting Ray Allen going, but the lethargy that soon crept in clearly impacted that plan. Allen put up nine shots in the first quarter, scoring 10 points, six on 3-pointers. But the screens soon disappeared, and Allen attempted just one more shot the rest of the half and only three after intermission, not hoisting a single attempt in the fourth quarter despite playing all 12 minutes.
That's almost absurd. In a half-court set, which Boston operated out of almost exclusively Saturday, the Celtics rely on their ability to move opposing defenders by forcing them to scramble to cover shooters who pop open -- most notably Allen, whose ability to draw help defenders often creates open shots for others.
The Celtics didn't set screens Saturday. They didn't move the ball. They labored through 28-of-74 shooting (37.8 percent) with Glen Davis putting up a team-high 17 shots in 43 minutes.
"Over the last five or six games, Glen Davis is actually leading us in shot attempts," Rivers said. "I love him, but that should never happen."
Just how important is it for the Celtics to get Allen shots off screens? Boston is 10-0 this season when he scores at least 20 points, and according to stats from Synergy Sports entering Friday's action, more than 30 percent of Allen's point output is generated on shots off screens.
Coming off a loss in Detroit in late December, Rivers lamented his team's pick-setting and suggested it was the reason Boston had lost two of its previous three games (and was about to lose its next game to New Orleans).
"We have to do a better job of setting picks," Rivers said. "Our pick-setting has been horrendous. Ray lives off of that, so we have to have an antenna up. The players on the floor, they have to get him shots. and we're not doing a good job of that."
Maybe it's not surprising that Rivers reinforced that to his team through video study this past week, and Boston rattled off four straight wins. The Celtics blistered the field in that stretch, no one more so than Allen, who was 37-of-58 overall (63.8 percent) and 13-of-18 (72 percent) beyond the arc, averaging 22.8 points.
Screens lead to open shots for Allen, which in turn opens up the floor for Boston's other shooters as the opposition scrambles to cover Allen. It sounds simple, but it all comes down to the thankless task of setting the endless array of screens that Allen runs through.
"Listen, it's no job that anybody wants," Rivers said. "Who wants to go around setting picks? But on our team, it's very valuable because we have players that need picks to get open. I think that's something very much like defense, that we have to remind them. Ray is not getting open, and we have to get him open. We have to get Paul [Pierce] open, so I think we have to do that more and more."
Although the Celtics generate only about 8 percent of their points off screens, the importance cannot be understated (particularly the trickle-down effect that comes as a result of extra passes). According to the Synergy Sports numbers, the Celtics attempted 245 plays off screens, which was second-most in the league behind only the Utah Jazz. Boston also ranked third in the NBA in points scored off screens.
Just how effective can those screens be?
According to ESPN Stats & Info, Allen made all nine shots he attempted off screens Wednesday night against the Spurs, generating 20 of his game-high 31 points that way. Allen was 4-of-7 for 11 points on all other types of attempts that night. His hot hand helped Boston shoot 61.3 percent against a Spurs squad that's among the best defensive teams in the league.
Screens lead to open looks, which leads to easy baskets.
Allen leads the NBA in plays off screens this season, running off screens on 33.7 percent of his touches. Only two players in the NBA use screens for more than 25 percent of their offensive plays -- Allen and Chicago's Kyle Korver.
Considering that 17.4 percent of Allen's touches come in transition and another 20.2 percent are spot-up jumpers, it's amazing that so many of his offensive looks require his teammates' grunt work.
And on Saturday, his teammates didn't create space for him, which is why Rivers might again have to stress the importance of screens.
"It's a film thing," Rivers said. "It's better to reinforce in practice, but when you don't have practice time, you reinforce it by film -- by showing the ones they're not setting. It's not the most positive way of doing it, and I'd rather work it out on the floor than using film, because it's always a negative weapon, but sometimes you do it."
Saturday's loss was a reminder of the perils of not putting in that effort.
"Offensively, from the start of the game, we didn't create any rhythm," Allen said. "It is [surprising] because [the offense] has been pretty good. [Saturday] was definitely a break from the normal, from what we were doing offensively. For whatever reason, this was an example of why we lose games. Statistically, it's so glaring."
Zero shots for Allen in a fourth quarter that opened as a one-possession game. Credit the Bulls for their ability to chase Allen around the court, but don't let it screen the truth: Boston sputtered because it didn't do enough to get Allen and its other shooters open.
Chris Forsberg is the Celtics reporter for ESPNBoston.com. Follow him on Twitter.