A career 42.2% in 3-point area and shot 42.4% last season. He has been a good 2nd unit hence, they gave him this kind of contract. With how expensive the Celtics are right now, this is kind of surprising that they will give this huge contract to a role player. I mean you have 2 players who have a contract of more than $300M in the next 3-5 years. I believe they're making a gamble right now since with the new CBA, their draft pick will be affected because they're expensive.
That's the thing with Boston Celtics right now, they have every right to keep the team after winning their 1st championship with Tatum and Brown. But it's not a two player, they will have to sign up most of it's role player too, including Hauser and he had games as well wherein he contributed in offense as he is one of the best shooters we have in the league right now.
However, they are now over the salary cap and so they will have to pay the luxury tax right now. So it's really hard to maintain this kind of money specially if the team will not have a good performance. So it's really a gamble for them to pay their players with good salary this season.