Question one
Do supermax contracts make players worse?
No. The decline is real, but the contract does not cause it.
Supermax players post the worst raw decline of any group, about -0.63 in impact on average. That looks like proof of a penalty. It is not. Supermax players are elite veterans. They are older, and they sign right after a peak season. Both facts predict a decline on their own. Control for age and prior performance, and the supermax effect is +0.48, not negative, and not statistically significant. The confidence interval spans zero in both directions. The decline was already baked in by who these players are.
Only 13 players signed supermax deals in this window. The test is underpowered. There is no sign of the hypothesized penalty, but a small effect cannot be ruled out.
Question two
Does performance regress to the mean?
Yes. Strongly, and in one direction.
Sort players into four groups by their impact before signing. The pattern is clean. The bottom group, coming off weak seasons, improved by +1.07 on average. Only 24 percent got worse. The top group, coming off the best seasons, dropped by -0.80. Seventy-one percent got worse. The two middle groups sat in between, in order. A regression confirms it. Every point of prior impact predicts a -0.25 drop afterward, about as certain as a result gets, across 2,378 events.
This is the engine behind the supermax mirage. Supermax players are top-group players. They decline like every other top-group player, contract or not.
Question three
Does changing teams help or hurt?
It hurts. That runs against the fresh-start idea.
Players who changed teams declined by -0.345 in impact compared to players who stayed. The result is strong and statistically clear, across 835 events. The fresh-start effect, which opened this study, predicts the opposite. A new situation should help. In this data, it does not.
One caution. Players do not move at random. Teams often let go of players who are already slipping. So part of this gap is probably about who gets moved, not the move itself.
A note on the team page
Read the team rankings as description
The team page ranks franchises by how their signings performed. It is descriptive context, not a scorecard. Teams with young, rising rosters look good because their players were due to improve. Teams built around aging stars look worse because those stars were due to decline. The ranking reflects roster age and timing more than front-office skill.
The full numbers are on the overview page. The sandbox page lets you explore the mean-reversion pattern yourself.