Malcolm Brogdon is a good basketball player. He is probably a very good starter with a nice two-way game, and he's in his early prime. He'd be a great acquisition at like $15m a year if he were unrestricted.
However, too many people are overrating his defense and overrating his 3 point shooting in talking themselves into chasing an important role player on a contender in a cushy situation who happens to be restricted at any cost.
Shooting
Malcolm Brogdon only takes wide open 3s. 3.1 of his 3.8 3PAs per game are uncontested. He takes 0.7 attempts a game with a defender within 6 feet. In this context, his 40% 3P% is really not impressive at all. Rondo looks like a great 3 point shooter the past six or so seasons because he gets a ton of uncontested open looks. Hey, guess what - Rondo takes a higher ratio of contested looks (29%) than Brogdon does (18.4%). That's an extremely low ratio.
Guys who shoot 40% with less than half, a third, a quarter of their shots being uncontested, and twice the three point ratio - that's legitimately impressive. Pretty much every big high volume 3 point shooter - Curry, Klay, Khris, hell even old Wes Matthews - actually commands major defensive attention so isn't shooting a ton of uncontested shots relative to the total.
This is why Brogdon's 50/40/90 thing doesn't blow me away. 40% on threes isn't that hard if you only take open ones and passing up on contested ones.
Brogdon is Milwaukee's fourth option on offense and draws the weakest defender because he's the only one out of Bledsoe, Middleton and Giannis who can't create his own offense. As opponent double Giannis and Middleton, he gets open looks. He'd get open looks here too next to Luka and KP, for sure, but the idea we should max him on the basis of his three point shooting is just stupid. We could tell any semi-decent shooter "hey, avoid taking any 3s if you're defended" and most could probably hit 40%.
Defense
Brogdon is a good defender, but he's not elite nor will be the anchor of your defense.
He's also on a team stacked with good to great defenders - Bledsoe, Snell, Middleton and Giannis are all excellent.
However, Brogdon really struggles to keep in front of smaller and faster defenders. He's not extremely fast. One of the main points of signing a nominal PG is because Luka can't defend elite PGs. Guess what - neither can Brogdon. That's why the Bucks got Bledsoe.
So let's be real here - Brogdon is a wing and not a PG, and he's not necessarily taking the other team's best player when Middleton might be doing that if they are bigger. Brogdon pretty much sticks with SGs. All his defensive stats are pumped up by being on a great defensive team. He's not having to cover for his teammates' weaknesses.
On both ends of the court, Brogdon is in a cushy situation that makes him look better than he actually is.
In a bigger role, he might be exposed.
Other factors
When you combine the fact that his defense and shooting doesn't seem so amazing in context with his age
(not young enough to bank on a massive upside), injury history (missed half a season last year and over 20 games this year) and his restricted status (on a team that may decide to match all offers because they're already in contention and he's still early prime), Brogdon is a really horrible target for us.
If we overpay, he will never be able to live up to that contract.
If we don't, Milwaukee probably matches.
So why are we wasting our time repeating our Parsons mistake? Brogdon is the guy you target after all the other options have been exhausted, and even then you do so carefully and not desperately.
EDIT: The most damning part of all: with a defender within 6 feet Malcolm Brogdon's 3P% is...31.1% - and that's ALL under "defender within 4-6 feet", which is still considered "open". The dude gets spooked if a guy is remotely close to him. His 45.7% on wide open shots is plenty good, but that explains why his 3P% falls to 40% in spite of the high ratio of wide open shots. He's shooting 31.1% on the remaining 18% of contested shots he takes.