Wade and Bosh went from teams that had losing records in 2010 straight to four straight NBA Finals when they joined up with Lebron. Kyrie and Love are doing the same right now.
And the only "all-star teammate" Lebron had in Cleveland was Mo Williams...who otherwise is a nice 6th man, if you want a 6'2" shooting guard who can't defend and has trouble making decisions off the dribble.
Bosh, a career 49% shooter, shot 54% and 52% in his last two years with Lebron, then immediately dropped to 46% this year when Lebron left. He hit 74 threes last year alone after only hitting 50 combined in his 7 years with Toronto. He became known as an elite defender after that not being part of his rep before. And if you like advanced stats, Bosh's best TS% years were with Lebron and his best ever win shares year happened with Lebron too, even in his reduced role.
Wade's 4 best shooting seasons were his 4 seasons with Lebron. A career 48% shooter hit 52% and 55% the last two years, then fell back down to 48% when Lebron left. His best TS% was with Lebron too. Wade had already had tons of injuries and was on the decline (nearly 30) when Lebron came into town, but having Lebron on the team gave him the luxury of being able to take off 20 games a year, definitely improving his longevity.
Irving, a career 45% shooter, is hitting 47% this year and having his best three-point shooting year ever. Even with Lebron and Love taking a lot of shots, he's only 0.6 away from his career best scoring average. His TS% is easily his best ever, his win shares are through the roof better than ever before, and his PER is a career high.