Warwick Jungle is completely busted in solo queue.
He is just beyond oppressive because in solo queue player do not understand how to counter him. If he invades at level 1, often times your allies will simply ping him if they notice; expecting their own Jungler to contest… But this is a HUGE mistake. Warwick is by far the fastest at clearing jungles bar none. And he 1v1’s almost any champion at level 1 with zero counters. Even Xin Zhao cannot compete at level 1. This means 1 of 2 things. Either:
Your allied jungler counter invades in the opposite side and equalizes (although this is a problem as Warwick is faster and end up taking 2 jungles for 1 with a forced engage in the final quarter.
You contest and bring an ally over to gank and kill him, but this enables the empty lanes to be pushed.
However, this is still a problem due to the small map and low death timers early on as Warwick will just repeat the process over and over again. This forces your team to constantly babysit jungles and as the game goes on the lanes will slowly get pushed in. Warwick does not even need to clear a full quarter, he just needs to clear a single camp and then run away to the other camp due to his movement. If Warwick gets one camp and a kill on the allied jungler then dies, this is a net win for the enemy team as your team is down a camp and a jungler with the enemy team being only down a jungler.
This result in the enemy Warwick dying a lot, but not caring as he keeps on emptying allied jungles faster than your team can respond without losing lane presence.
The only real counter is to kill Warwick and then hunt down another enemy and kill them. This does not always work however as many times the enemy team will simply run and sit behind a tower while the Warwick revives and goes straight back to invading jungles while your team is distracted at an enemy tower.
Of course, in a team where you are grouped up and communicating this is not as big of a deal, but in solo queue it is a nightmare.
This makes Warwick absolute S-Tier in solo queue if the Warwick understand how he can abuse the small map size and low death timers in the early game by simple farming enemy jungles and then dying without a care in the world.