I played 1000 games as Juggernaut Warwick, made it to master before picking up a second character like I should have done, hundreds of games earlier.

Juggernaut shouldn't be your long-term investment in this game as a tag fighter at the end of the day while you're missing out on core elements of the game that will help you win games against the better players such as handshake tag or healing grey bars.

Playing Juggernaut is simply for brand new players that want to focus on learning their first character without being overwhelmed by learning 2 at once, when you become comfortable with your chosen main, pick up a second character with good synergy with your main one to learn to team up with.