Offer Sheet compensation is based on the contract AAV.
Deferred Salary will change the contract AAV—how much deferred salary in any contract changes the AAV depends on the amounts deferred, length of deferment, and current interest rates.
When a contract includes Deferred Salary, the NHL calculates the NPV (net present value) of the deferred money. That NPV formula determines the % of the deferred salary included in the AAV calculation.
Hypothetical Example: player A defers $1m of salary for one year. The league formula for NPV determines every deferred dollar paid one year later is worth 3% less than a dollar earned when the original salary was due. When calculating the contract AAV the league will include $970,000 of the salary paid in the AAV, not the full $1,000,000.
Why don’t more players sign deferred salary contracts? Generally, deferring money is a net negative for the player. If the player has a competent investment strategy the time value of money paid sooner will usually be better than waiting for the larger % payment later. There are unique situations, especially with taxes or retirement where deferring money could have tax planning advantages.
Deferred salary predates the Salary Cap. When interests rates were close to 0% deferred salary would make a minuscule change in the contract AAV. It’s only in recent years where USA/Canada interest rates have hit 3-5% that bigger AAV impacts can happen.
The deferred salary calculation for AAV does appear to be a point of concern for the NHL. Wouldn't be surprised if the next CBA under negotiation includes changes.