perhaps the problem with rook is that theres practically not much variation in playstyle. either you go at least until towers 3 or you suck at playing rook. a few games ago i played with a slam rook against a tower rook and the slam rook just sucked. it was levi and that tower rook could build towers endlessly. he was supported by a sedna and we really couldnt do much about it.
its not that a pure slam rook cant be useful in a good team but he just cant run away and then needs to be safed which is a liability that mostly cant be handled when playing public. also when playing rook you cant follow a moving fight and the people mostly use the ranged attacks to slowly tear rook down. thats why gods strength aint a very useful skill for rook. if the enemy team gets into melee range they are certain they can win and either youre being saved or you gotta run which mostly ends in your death. if youre being saved then again you cant follow the fight when the attacker flees.
i guess the biggest problem with rook is that the people dont take towers or dont use them correctly 
what i would change about rook is
balance the tower skill in itself as i wrote above
slightly (really like 0.3 sec) buff the stun duration of boulder roll and add a minimal slowing effect of maybe 5% as aftereffect to it.
add a slight slowing effect to slam. which means that rook can escape easier after boulder + slam.
he shouldnt be faster. hes by design slow and thats good. hes got towers for that and mates can tele in but he should be rewarded if he can hit someone with boulderroll and slam by being able to get some distance between him and the attacker.
theres nothing i would fight over except that i really think that the tower skill itself aint balanced very well. i dont know what you could do about gods strength. perhaps you could add a crit chance or some other effect or something to make it a useful lategame skill but i think that rook really shouldnt be faster.