Even at 29 there's 3 good seasons in him. Look at Callum Wilson until very recently is still a good scorer at 30+ however he just couldn't stay fit. Wissa has demonstrated that he knows where the goal is and his injury record is very good.
It's all left a very bad taste but maybe we are a more rounded team with these 2. I hope the rat turns out to be as good for the bindippers as Andy carroll turned out to be.