It's complicated accounting for sure but in terms of the general fan debate, we'd get more out of debating the total, initial financial commitment to the player when they were signed??
It's still hard to guage..... EG Kane.... He's quoted as being on 210kpw afaik..... Truth be known he's assumed to be on more like 300k with goal bonuses and other such jazz.
Up until recently all our player contracts were highly incentivised.... Other clubs have their own approach.