2. The team is better without him
Let's put aside the fact that according to Cleaning the Glass, Obi Toppin had the 20th highest on/off differential among 255 players to see at least 1000 minutes of court time last season, whereas Julius Randle had the 6th lowest among that same group. To some, that stat by itself is enough justification for trying everything possible to move off of Randle and insert Obi Toppin into the starting five.
But on/off differential isn't everything. If it was, Isaiah Hartenstein would have gotten the max instead of a two-year, $15 million deal. What's undeniable, however, is that other than a half-season stretch playing in front of empty gyms, New York's offense has consistently been better with Randle off the floor:
2019-20 season: New York had a higher offensive rating (107.1) with Randle on the floor than off (105.3), but those numbers are a bit deceiving. For one, the Knicks bench was dreadful that season. More importantly, according to Cleaning the Glass, when Julius played without Marcus Morris, the Knicks scored just 105.7 points per 100 possessions, whereas Morris lineups without Randle scored 110.4 per 100. Randle's on-court offensive rating would have ranked in between the 29th ranked Bulls and the 30th ranked Warriors.
2020-21 season: Julius started the season off on the tear of all tears, with a 53.7 effective field goal percentage before the All-Star break, spurred largely by some ridiculous shooting on long twos. They needed every bit of that productivity, as New York scored just 101.9 points per 100 without Randle on the floor. At the same time, the on-court offensive rating of 109.4 with Julius shooting flames out of his butt was still a bottom-ten number. After the break, Randle's eFG% dropped to 49.7. Not coincidentally, the Knicks offensive rating increased from 110.7 when he played - still bottom 10! - to 113.5 when he sat.
2021-22 season: The Knicks offense plummeted to 108.0 points per 100 possessions when Randle was on the court, a number that would have slotted them between the 26th ranked Rockets and the 27th ranked Blazers. With Julius off the court, the number increased to 110.5.
I'm only citing offensive numbers here a) because that is supposed to be his strong suit and b) because anyone with working eyes doesn't need data to support their critique of Randle on the defensive end. When he tries, he is more than passable and occasionally downright effective. When he doesn't, it is a team-wide soul-suck that would make Shang Tsung blush. That brings us to ...