For every action, there must be an equal and opposite reaction. Hard-core geeks know this as Isaac Newton's third law of motion, but basketball fans are familiar with the concept in a much simpler way: If some players improve, others must get worse, relative to the league.
Along with that unfortunate reality comes the unpleasant actuarial task of identifying who, exactly, these players will be. For 20 players to break out this season, as I projected earlier this month, an equal number must take steps backward.
Thus, once again, I present the All-Decline Team. And as with the All-Breakout Team, it's time to look back at my performance from last season. A year ago, I nominated 23 players to the team; while three of the predictions turned out to be spectacularly wrong (Caron Butler, Manu Ginobili and Andre Miller), the other 20 players had declines that ranged from slight to severe.
Again, "decline" is always relative -- if I pick an All-Star to decline this season, I'm not saying he's going to suddenly turn into Brian Cardinal. I'm just projecting that the numbers he puts up this season won't be as good as the ones he put up last season.
Undoubtedly, a couple of these guys will buck the trend. Nonetheless, I expect at least 16 of them to be worse this season than they were in 2007-08. So without further ado, 2008-09's All-Decline Team:
Group I: The Fluke Rule guys
Usually, I depend on Fluke Rule players to build a quarter of my All-Decline roster, but they're a scarce breed this season. Only four players qualify for the Fluke Rule, rather than the usual six or seven. Of those, one will miss most or all of the season (Brendan Haywood) and another doesn't have a team yet (Bonzi Wells). That leaves me with a two-man Fluke Rule roster.
The Fluke Rule, if you aren't familiar, states that a player who is older than 28, has a Player Efficiency Rating higher than 14 and increased his PER by at least three points from the previous season is 90 percent likely to perform worse the next season. Last season, the rule went 7-for-7 with Jamaal Tinsley, Mikki Moore, Darrell Armstrong, Chucky Atkins, Tim Duncan, Devin Brown and Ruben Patterson.
Brad Miller, Kings
Miller, 32, had a sweet bounce-back season in 2007-08, but I'm suspicious of his ability to maintain such a high rebound rate (it was 16.0 after three straight seasons under 14) and he already is behind the eight ball thanks to a five-game suspension to begin the year. Throw in the threat to his minutes from youngsters Spencer Hawes and Jason Thompson, and his numbers could be down quite a bit.
Hedo Turkoglu, Magic
Turkoglu was 28 last season; 28-year-old Fluke Rule guys tend to drop off less harshly than their older brethren. In other respects, however, he's a classic Fluke Rule guy -- he'd never played that well before last season, he shot unusually well on long 2-pointers (48.5 percent, compared to 45.1 percent the previous three seasons) and he glided through the 82-game schedule without suffering so much as a hangnail.
Group II: Field goal flukes
This one has a simple explanation: Two-point shooting percentage is among the flukiest of stats. When a guy has a percentage on 2s that is far off his career norm, sometimes it's because he genuinely got better -- but much of the time it's simply random variation gone wild. Given their histories going into last season, I'm dubious these three guys can keep shooting as well this season:
Sasha Vujacic, Lakers
Talk about a jump in shooting percentages. In his first three pro seasons, Vujacic shot 36.5 percent on long 2-pointers and 34.3 percent on 3s; last season, he made 45.2 percent of his long 2s and 43.7 percent of his 3s. The truth on Vujacic likely lies somewhere in between the two extremes. It means he'll continue to have value but won't match the type of numbers he put up last season. A preseason ankle problem and a possible loss of minutes to Trevor Ariza are other factors working against him.
Mo Williams, Cavs
Even with LeBron James around to create open shots for him, Williams might have trouble replicating last season's numbers. For one, the difference in open looks between Milwaukee and Cleveland might be overblown -- the Cavs (19th in offensive efficiency) were nearly as bad as the Bucks (22nd) at the offensive end last season.
Second and more importantly, Williams shot 51.1 percent on 2-pointers last season. That's good, of course, but here's the problem -- it also was far better than he'd ever shot before. Over the previous seasons, he had made only 46.1 percent from that range. The change in scenery might cushion the blow a bit, but expect his shooting percentage to go down.
Derek Fisher, Lakers
Fisher's first season back in L.A. was quite a turnaround, as he hit 45.3 percent of his 2s after making 41.1 percent over the previous three seasons; his 43.6 percent overall shooting mark was his best in half a decade. In fact, he was nearly a Fluke Rule qualifier. Given that he's 34, that his shooting mark is likely to return to earth and that Jordan Farmar is breathing down his neck for playing time, he's a good candidate to see his numbers regress this season.
Group III: Guys who probably were over their heads
For these guys, it isn't the 2-point percentage so much as the overall picture -- each was far better than expected last season, and each had or has injury questions in the preseason or opening games this year. Also, I'm highly suspicious of each's ability to provide an encore performance.
Mike Dunleavy, Pacers
For five years, Dunleavy couldn't shoot straight. Then all of a sudden last season, he couldn't miss -- he shattered his career highs in 2-point, 3-point and free-throw shooting. We probably should expect some regression to the mean on that front, especially since he's past the age at which guys typically make giant strides in performance.
Additionally, he's been dealing with a knee problem since training camp and sat out the Pacers' opener.
Carl Landry, Rockets
Landry was so good in his limited minutes last season that he had a higher PER than Carmelo Anthony. Any takers on a repeat? While he's unquestionably a very strong frontcourt reserve, the odds of his averaging nearly a point every two minutes while shooting 61.6 percent from the floor are incredibly small -- for instance, in college, he shot 59.7 percent as a fourth-year senior, with a much higher turnover rate than he had last season. His insane productivity last season was a welcome surprise, but I'm not ready to extrapolate a 711-minute sample into full-blown stardom without much stronger evidence from his college years.
James Jones, Heat
In this case, it's the 3s as much as the 2s. Jones was playing as far over his head as any player in the league in the first half of last season, keying the Blazers' 13-game win streak by making virtually every 3-pointer. He finished at 44.4 percent for the season, a number he's highly unlikely to equal in future campaigns (he couldn't break 40 in his two years in Phoenix). His 2-point percentage also was above his career norms. He's out for several weeks after hurting his wrist.
Brandon Bass, Mavs
I can buy that Bass is an effective face-up scorer when he works against opposing big men. But a 54.4 percent shooter on long 2s? Sorry, I'm gonna need more evidence for that one.
He was a nice find, but I don't think it's reasonable to expect him to shoot quite so well this season.
Group IV: Older guards who can't shoot
One group of players that consistently has trouble keeping up its performance is guards who shoot poorly and are hitting or just past age 30 -- in particular, small guards who fit this description. If they lose a step, they have nothing to fall back on, and this is the age when most players lose a step.
Andre Miller, Sixers
Yes, I'm back for more. I was down on Miller last season, and he punished me with arguably his best season. Well, now I'm doubly down on him. For starters, he was very nearly a Fluke Rule player. More importantly, he fits the very definition of a guard who typically fails in his 30s because he's a dreadful long-range shooter. Granted, he looks like he's in better shape this season -- he even blocked two Jose Calderon jumpers in the first half Wednesday. But all the trends point against him.
Rafer Alston, Rockets
He's 32 and a wayward marksman, so he fits with the general Miller corollary above. Additionally, last season was an up year by his recent standards, as he improved to 39.4 percent from the floor (if that can be called improvement), with all the increase coming on 2-pointers. Usually with 2s, it's a case of what goes up must come down, especially at this age; if so, Aaron Brooks and Brent Barry might slice deeply into his minutes.
Allen Iverson, Nuggets
I know it's uncouth to question "The Answer," but Iverson is a small speed demon with a shaky stroke, making him a strong candidate for decline at age 33. His past two seasons weren't nearly on the level of his 2004-05 and 2005-06 campaigns, so the descent appears to be already in progress. With Iverson battling knee and ankle problems, expect less rather than more.
Group V: Bigs with bigs
Pairing two hulking big men sounds good in theory. In practice, they often get in each other's way -- the most vivid example being the Eddy Curry and Zach Randolph experiment in New York last season. So it is that when one established 7-footer joins another, at least one inevitably suffers.
Marcus Camby and Chris Kaman, Clippers
Camby and Kaman combined to average 25.8 rebounds and 6.4 blocks while playing in different cities last season. So I guess that means they'll combine for 25.8 and 6.4 as the starting frontline for the Clippers, right?
Um, wrong. There are only so many rebounds to be had, people, and inevitably, they're going to be taking them off each other's plates. The same goes for blocks -- only one big guy is positioned to rotate from the weak side on many plays. Camby and Kaman each will be solid in his own way, but there's no way their rebound and block numbers won't take hits.
Check that -- there is one way. This scenario won't happen if the two are never on the court at the same time, and each gets injured enough that this is possible. So far, Camby hasn't played even a preseason game.
Pau Gasol, Lakers
I've written about this plenty already, but the return of Andrew Bynum is going to make things a lot harder for Gasol offensively. He's going to lose a lot of low-post touches to Bynum, and while he's an effective high-post player, he's a lot more dangerous when he's on the block. People don't really think of him as a go-to post guy because of his skinny frame, but he is; that aspect of his game now will take a back seat.
Group VI: The traditional Western powers
I mentioned the East as one of my All-Breakout performers, and for that to be true, it stands to reason that the West must take a fall. In particular, I'm guessing the former holy trinity of Dallas, Phoenix and San Antonio will fall on some hard times, at least relative to its previous glory. I projected all three to make the playoffs because, looked at on a one-by-one basis, you can't pick them to finish behind the likes of the Nuggets, Warriors and Wolves.
However, in the aggregate, you can reach a different conclusion. When you have three teams like this, with each facing serious age issues and with San Antonio facing at least one fairly serious injury question, there's a good chance that across the three, one of them will have a nasty surprise in store for us.
I don't know which one, but let's say there's a 25 percent chance per team that the Suns, Spurs or Mavs faceplant -- which seems plausible, given that each is an injury away from such a scenario and that each has several key players who are old enough to suddenly lose it.
If you buy that, you end up with a 58 percent chance that at least one of the three will take the plunge this year. In other words, in the case of any one of the three, it would be unexpected. Across the trio, however, there's a decent chance we get one collapse. I don't know which one it will be yet, but based on the opening week results, you could make a case for any of them.
John Hollinger writes for ESPN Insider. To e-mail him, click here.