"The worst good team against the best bad team" might not make for a great tag line, but when the Bulls and Suns meet Friday night (10:30 p.m. ET, ESPN), that description won't be too far from the truth.

Since Phoenix is 25-18 this season while Chicago is just 18-22, it might seem as if the Suns should be overwhelming favorites. But look a little deeper and this matchup is an interesting one because of how the past month has gone for each team.

The two clubs are going in opposite directions at the moment. Phoenix might earn the honor of "worst good team," given that the Suns are 11-15 since the start of December and had dropped four straight before a win over hapless New Jersey on Wednesday stopped the bleeding.

In a Western Conference in which 11 teams are vying for eight playoff spots, it's little solace that the Suns remain seven games over .500 -- they have only a 65 percent chance of making the postseason according to Friday's Playoff Odds.

The Bulls, meanwhile, are 8-5 over the past month, including wins over Orlando and Boston, quelling mounting speculation about coach Vinny Del Negro's job status and putting Chicago into the No. 8 position in the Eastern Conference playoff race. They're essentially locked in a three-way battle with Milwaukee and New York for the East's final playoff spot, with Friday morning's Playoff Odds giving them a 35.8 percent shot of grabbing it.

• Read the rest of Friday's PER Diem.

Garnett

Just in case last season was not evidence enough, the past 10 games have only reinforced what was already obvious: The Celtics need Kevin Garnett. Badly.

Last season with Garnett in the fold, the Celtics were 44-13 and seemingly destined to repeat. Without him, they stumbled to an 18-7 record, 25-14 if you include the postseason.

This season, the Celtics are once again winning about 75 percent of the games in which Garnett has played (22-7). Without him, they are reeling, with losses in six of their past 10.

So yes, the Celtics are better off with the future Hall of Famer on the court. That goes without saying. His expected return Friday is a welcome momentum shift for a Celtics team that hasn't used its regular starting lineup since Dec. 20.

But why? What is it about Garnett that's so valuable? Why, despite having added Rasheed Wallace, are the Celtics unable to survive without him?

One word: defense.

Garnett no longer needs to be the offensive force who averaged 20-plus points per game for nine straight seasons. He hasn't scored more than 26 points in almost two years. Wallace and even Glen Davis are capable of putting up the 15 ppg that Garnett now averages. That's not replacing Garnett entirely, but with Ray Allen and Paul Pierce in the fold, the Celtics can afford to give up some offense.

• Read the rest of Lundblad's story at ESPNBoston.com.