With all three players having come from different teams, there will assuredly be a learning curve if they're ever assembled on the same line. However, their track record has shown that their best brand of hockey comes out when they're playing with players that match their skill sets.
Maccelli, Roy, and Joshua would give the Leafs a third line rich with skill, size, and physicality. They can play gruelling minutes, while providing secondary scoring, and you can trust them in al situations.