As discussed many times before, we are going to see crazy money given out this off-season because of how much the cap rising. A max this year will not be the same as the max next year (and the next). Harris at the max isn't necessarily a bargain, but will seem much more reasonable in a couple of years. Guys like Harris, Middleton, and Monroe are not typically max-level players, but the the good news is, there will be plenty of other guys making much more money than them in future years.
Monroe is a far, far, far better player than Harris. Harris is not even close to his level. I'd say Monroe is at least two levels above Harris. Now take in to account the fact that some people still question whether Monroe is worth a max contract - that should give you some indication of how far Harris is from being a max contract player.
Even Middleton is easily a level above Harris because he's a borderline elite shooter (while Harris is merely a 'good' one) and is also an extremely good defensive player (while Harris is a TERRIBLE defensive player).
Realistically, Tobias Harris is worth no more than Avery Bradley and Jeff Green.
Harris has value over Bradley because of his size and rebounding, but Bradley has similar value over Harris because of his defense and his athleticism. The two guys are essentially dead even in terms of value.
Harris has value over Green because of his youth and his slightly better rebounding, but then Green has value over Harris because he's taller, longer, a far superior athlete, and a much better defensive player. Again, pretty much equal value.
So in other words, if you are paying any more than about $8M - $10M a year for Tobias Harris, then you are overpaying. Giving him $17M a year is drastically overpaying.