Monta is one of the most polarizing players in the NBA.
Drafted very late in the 2nd round - Underrated.
Wildly exceeds those expectations, which then always leads to a massive pendulum swing in the other direction - overrated.
Puts up very good "traditional" total numbers (pts, rbs, assts, stls, blks) - further overrated by "old school" crowd ("he puts the ball in the basket," etc.)
New school crowd comes along, looks deeper. Since his rookie season, he's been averaging close to 40 mpg, which makes his total numbers less impressive. .455/.316/.733 career percentages, so he's not that efficient, which means he's shooting a lot but taking looks away from people who are more efficient at getting the ball in the hole, so he's actually diminishing his team's total points. TS% further backs that up, with one very good year (58%, his 3rd year) and other than that, nothing above 54.5 and usually well below that mark. Except for that one very good year, scoring/shooting wise he's similar to Rondo, who is quite a bad shooter. Ellis just shoots more. This year his TS is tied for 272nd.
Then they look deeper at team stats. His net +/- has been: +2.4, +2.6, -6.2, -11, -0.8, +4.9, +2.7, +2.8.
So there looks like there's a lot of noise there, but it's clear that he does not consistently make his team better when he's on the floor than when he's on the bench. Some years, in fact, the team is way better with him sitting.
I personally think that the average pendulum is probably appropriately swung, since he's either incorrectly regarded as an all-star or incorrectly regarded as useless. I love the JR smith comparison (in terms of impact, not style). He should be a 6th man or 4th best player kind of thing, like Terry in his prime, or stephen jackson's first stint on the spurs, etc. He should not be the focal point of the offense, or an all-star; he has too many holes.