Giving max money to non-max players is a mistake. I know he is young, and has decent numbers, but what impact does he have on winning?
But you have to define what a max contract is. Just estimating the numbers, it will be about $16 mil for Harris this season. For an older veteran, it is about $22m. With the salary cap going up to $89m next year, it will be about $20m for a young guy and $28m for an older guy. In 2017, with the cap going up to $108m, it will be about about $25m for a young guy and $34m for an older guy, meanwhile Harris will be locked in at around $17m that year.
If Harris improves at all, and he's only 22, that contract will be a bargain. Considering he plays a position of need and his youth, this seems like an easy decision to me.