The thing is that in basketball one player can make a much more significant impact than in baseball. Consider that the elite players have the ball in their hands over a third of the time, while playing close to 40 minutes a night. They are directly responsible for a team winning a game whereas Mike Trout will be involved in maybe 4 or 5 game changing moments over the course of a game if he's lucky. That's the reason why when people talk about LeBron's teams they mention his impact specifically, because him being on the court can be the reason for a team making the playoffs, like what happened in his earlier Cleveland tenure when his supporting cast was mostly terrible.