Roshi is not a tank, but many here (not iamascrub) continue to think he is just because he stacks defense. Roshi in arena needs to be exposed to damage but not to the highest part of it. Works well with han or hokage minato or with bee sst that shields him or behind clones. Hardly even kimimaro, that's a real tank, survives if fully exposed to damage with no shields or defense buffs.

Stats growth are the boost per level up they gain but don't show at all what are the basic by default level 1 stat they own.

1000 + 10*level is still lower than 1500 + 7*level at level 100 and those growth stats are only the 10 and 7 coefficients i showed in this example.

Gaara kk, moreover, isn't either a full tank. Gaara normal is the tank version, gaara kk is the striking version. And still kk gaara have, by looking at the growths you posted, 1000 more hp and higher defense and resistance growth + superarmor and self shields in round1.

What is your definition of a tank? Mine and the common meaning of it is somebody able to endure hits if in front row. Does roshi survives in front row in arena without shields and/or healings from other ninjas after round1 if comboed? No, he doesn't do it, so is not a tank.