That worrying sign could be that Robertson's future with the Maple Leafs is coming to an end soon. Ever since Robertson's holdout, it feels like he doesn't want to be here, and as much as he was disrespected by former coach Sheldon Keefe, he hasn't proven himself this year and has been a detriment on the ice.
Toronto can definitely benefit from Robertson when he is producing though, as he scored 14 goals in 56 games with limited ice time, so the potential for him to be a 20+ goal scorer every year is there. The question is, do the Maple Leafs want to wait around forever until Robertson breaks out? If his consistency is so hot and cold, Toronto risking losing games and money due to Robertson is counterintuitive for their success.
If Toronto comes into Seattle and dominates the Kraken, finding a new chemistry and life with a rejuvenated John Tavares and playing the kind of hockey Craig Berube wants; it might be hard to justify keeping Robertson when they can get a good return for a player sitting in the press box and he'll pack his bags sooner than later.