Nearly Everything That Had to Do With Season 5 Was a Buff to Warwick
1. HARDER JUNGLE
Warwick is the ultimate sustain jungler, right up there beside Fiddlesticks. Since Warwick has the opposite issues sustaining in the jungle, Warwick was unaffected by the harder jungle like many other sustain junglers.
2. NEW JUNGLE ITEMS
The new jungle items gave Warwick exactly what he needed... more on-hit effects. The big part of this being a true damage on-hit effect. This allows Warwick to ignore a lot of defenses with his ultimate.
3. A MUCH MORE REWARDING EARLY DRAGON
Dragon is much more impacting early game now that it gives flat out stats. Warwick is one of the few junglers that can solo the Dragon very early and this gave him another strategic advantage over his opponents.
4. THE REMOVAL OF
EXECUTIONER'S CALLING
Ever heard of this item. Some of you don't, but this item applies grievous wounds on-hit to champions. This item was one of the main items for AD champions to counter Warwick due to his extreme healing and they removed this item.
5. CHANGE TO BARON BUFF
Warwick already has super sustain and can pick up Blue Buff very easily. The change to Baron Buff made the buff much more beneficial to Warwick by giving him increased pushing power and removing what he did not need.
6. ADDITION OF
RIGHTEOUS GLORY
This is not a major reason, but with this item Warwick is provided with enough time to out his enemy below 50% health in order to activate his movement speed boost. It also gives him a lot of extra stick.
Also, on a side note, 
Cleanse does not remove the suppression of his ultimate, but this has been in the game since his release.
Warwick is not broken, it is just nearly everything that has been changed this preseason benefits Warwick.
