At the start of the season, the notion that an injury to Robin Lopez could be crippling to the Phoenix Suns would have been laughable on several levels. First, the Suns have been far more competitive in the Western Conference than anticipated, and still have a chance at finishing as high as second in the standings. Second, Lopez has improbably been a big part of that success, averaging 11.3 points and 6.3 rebounds on 59.4 percent shooting as the Suns went 22-9 with him as a starter.
Now Lopez will be sidelined for at least the next two weeks with a bulging disc in his lower back. He will be reevaluated on April 12, at which point Phoenix should find out whether Lopez will be available for the team's postseason run.
Just how important is Lopez? The numbers tell something of a mixed story. Check out, for example, the team's splits for four different periods--the Suns' sizzling 15-2 start to the season, the next 24 games when they went 9-15 before making the change to the starting lineup and all of Channing Frye's starts compared to Lopez's starts. (Note that Sunday's win at Minnesota, where Jarron Collins started in place of Lopez, is not included.)
Period ORtg DRtg SOS ADiff
First 17 119.1 110.0 -0.9 +6.5
Next 24 113.5 114.4 1.1 -0.4
Frye 115.9 112.6 0.3 +2.5
Lopez 118.7 110.9 -0.9 +6.5
As compared to Frye's entire tenure, Phoenix has been much better at both ends of the floor and overall with Lopez in the starting five. What's interesting to note, however, is the eerie symmetry between what the Suns did with Lopez and how they started the season. Accounting for a schedule that was much harder toward the middle of the season, their adjusted point differential was exactly the same in these periods. While Lopez has gotten credit for improving the team's defense and has unquestionably helped on the glass, Phoenix has shown the ability to play and more importantly defend equally well with him out of the lineup. (Lopez missed the season's first 15 games after breaking a bone in his left foot.)
A look at the Four Factors shows that, though they were equally effective, the Suns' defense early in the season and recently were very different in style.
Period eFG% DR% FTA/FGA TO%
First 17 .496 .702 .250 .138
Next 24 .496 .684 .311 .133
Frye .496 .692 .286 .135
Lopez .488 .728 .307 .125
During November, Phoenix was very effective at keeping teams off the free throw line. Hacking opponents more frequently, combined with forcing fewer turnovers, caused the Suns' defense to regress. Neither of those factors have improved since Lopez moved into the starting lineup, but Phoenix's shot defense has improved slightly and his rebounding has been a major help in terms of what has historically been a weakness for the Suns.
Phoenix's drop on offense after a fast start is easier to explain. As Seth Pollack found in a similar analysis for the Bright Side of the Sun blog, the Suns were on fire from beyond the arc in the early going, making 44.5 percent of their attempts. A decline was inevitable, and Phoenix has since settled in at a more reasonable 39 percent or so. Lately, the difference has been made up for by Amar'e Stoudemire's torrid scoring, which has been credited to Lopez allowing him to play his natural position but ultimately seems more attributable to Stoudemire anticipating a big payday this summer.
There's another bit of hopeful news for the Suns in Lopez's absence, and it's that his net plus-minus is nothing special (+0.5 points per 100 possessions per BasketballValue.com; Frye is +6.5). How does this jive with the difference in results as a starter? While we're crediting all of the difference in Phoenix's play to the starting center, in practice the designation is probably somewhat overstated. Frye still played more than 20 minutes per game, nearly as many as Lopez, in a reserve role. He's certainly been a factor in the recent run too.
The interesting observation looking at playing time is that Lopez's minutes increased more than Frye's decreased, while Stoudemire and Louis Amundson were unaffected. Part of what's changed for the Suns is simply playing two big men together throughout the game instead of going small at power forward for between five and 10 minutes a night. To keep that rotation going, Alvin Gentry started Collins in place of Lopez on Sunday, and Minnesota outscored Phoenix by 11 points with the Stanford product on the floor. Any minutes going to Collins are too many (his net plus-minus, albeit in garbage time, is a dismal -11.4), and Gentry would be wise to consider moving either Jared Dudley or Grant Hill to the four for stretches, especially now that the Suns are deeper on the perimeter with the return of Leandro Barbosa. If he feels the need to stay with two bigs, stretching Amundson's minutes is the preferable option.
Add that all up and I'm not entirely sure what to make of Phoenix's chances. The optimist notes that more minutes for Frye are a good thing, since the Suns have played better with him in the lineup. The pessimist counters by pointing to how poorly Phoenix played with Frye in a starting role in December and January. Collins' presence, even for limited minutes, is enough to convince me the Suns are in trouble. Given the fluid nature of seeding in the West, this is much more than an academic consideration. Phoenix is in a fierce battle for home-court advantage in the first round, and it's not entirely inconceivable that the Suns could be passed by one of the three teams battling for the 6th-8th seeds. At this point, even a slight drop-off could cost Phoenix dearly.
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Kevin Pelton is an author of Basketball Prospectus.
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