Well… it gets down to how steep and soon the bonus escalates.
Sharp-inclining escalators seem more like buying shares in a stock that did really well last year then blindly assuming it will repeat at the same or better level of performance next year and beyond. I'd hate to base any sizable long-range contract bonus upon something that happens in the first year of said contract, especially if pre-contract, the player had a significant history of injuries. But, if it's a more of an exponential growth, I could get onboard.