I really don't think anyone is to blame for his lack of development without pointing first at:
The Toronto Maple Leafs Nick Robertson finally had a healthy season. Has he proved his value to the team? Can he find a regular lineup spot?
thehockeywriters.com
Suddenly, Robertson Began to Suffer Injuries
In his regular-season debut in January 2021, Robertson suffered the first of several injuries that would hinder his professional development: a knee injury that limited him to six NHL games and 21 American Hockey League (AHL) games with the Toronto Marlies that season. In October 2021, he
suffered a fractured fibula playing against the Manitoba Moose. As a result, he only played ten NHL games and 28 AHL games in the 2021-22 season.
Things did not get any better in 2022-23. On Dec. 22, against the Los Angeles Kings, Robertson suffered a season-ending shoulder injury that required surgery.
From the time he first stepped on the ice for the Maple Leafs on Aug. 2, 2020, in the pandemic-delayed NHL playoffs, and his 2023-24 season debut on Nov. 6, 2023, injuries and the pandemic limited Robertson to 31 NHL games and 60 AHL games. In those 31 NHL games, he produced just three goals and four assists. His AHL production was impressive, with 27 goals and 57 points in 60 games, but his injuries and lack of playing time hindered his offensive contributions.
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He should be treated like every other player that doesn't have a NMC in their clause.
If a trade makes the team better you make the trade.
That's what Leafs' fans would be after.