This one was simple, but oh so painful to watch. The Celtics got into Phoenix around 4 a.m. local time Friday night and started out in a not-surprising funk. By the end of the first half they had set new season lows for points in the first quarter (16), points in the first half (35) and they continued their futility throughout the second half.

Then they lost their coach after referee Steve Javie tossed Doc Rivers at the 4:33 mark of the second quarter and Glen Davis who strained his right hamstring. If that wasn’t enough, Kevin Garnett was ejected after low-blowing Channing Frye on a 3-point attempt.

The final was 88-71, which extended their run of futility in back-to-backs. Their last three have been particularly ragged with a loss 90-79 loss to Chicago that was their offensive low point before Friday and the 83-81 loss in Washington last week.

The Celtics return to action Sunday against the Lakers, who lost at home to Sacramento. Chances are good that both teams will be in a lousy mood for that one.

(For a complete recap, click here.)

WHAT WENT WRONG

Offensive stagnation: Unlike Thursday when the Celtics recovered long enough to put enough points on the boards and beat the Blazers, the C’s never got into any kind of a rhythm. That’s discouraging because the Suns are one of the worst defensive teams in the league. Back-to-back or not, there’s simply no excuse for the Celtics to shoot 34 percent in the first half, or turn it over six times in the first quarter against the Suns.

Much of the blame for the Celtics offensive woes falls on Rajon Rondo. He had a miserable night on both ends of the floor, scoring just seven points on 1-for-6 shooting and registering more turnovers (seven) than assists (six).

Glen Davis missed the second half with a hamstring injury: This could be a potentially bad blow for the Celtics because Davis is their most important bench player and the key to their frontcourt versatility. The Celtics don’t really have another backup power forward on the roster (Luke Harangody is next in line), but Davis has become much more than just Garnett’s replacement. He also plays important fourth quarter minutes at center, which makes him a matchup nightmare in his own right.

Hamstring injuries are notoriously difficult to calm down — Rondo’s lingered weeks after he was supposedly healthy. If Davis is out for any length of time, the Celtics could have a serious problem.

They got nothing from the bench: Before the Celtics pulled their starters, their bench players had scored 15 points on 6-for-20 shooting. Nate Robinson couldn’t provide a spark and Davis did little before his injury. Von Wafer got some early minutes, but the shots just weren’t there for him either.

This has been a constant theme for the Celtics this season and while Rivers hopes to cobble together a coherent second unit after Delonte West returns from his broken wrist, the bench has been a huge disappointment to this point. With the amount of talent the Celtics have they don’t need their bench to win them games very often, but there are nights when they need a change in direction and energy and the second unit has provided neither on a consistent basis.

WHAT WENT RIGHT

The Celtics fought it out (literally): Give them credit for not packing it in when they could have, but they couldn’t get the lead under 10 in the third quarter and make a serious run. They did cut the lead down to 11 after Mickael Pietrus elbowed Garnett and picked up a technical foul. That seemed to energize the Celtics for a bit, but with a chance to cut the lead to single digits Marquis Daniels was whistled for an offensive foul in transition. Their last chance evaporated after Garnett’s ejection.