Past a certain point, udyr becomes a poor choice. Because his only option is > run directly at person, competent warding shuts down his jungle, and smart play ruins his top lane. It works when people are dumb and forget to ward when overextended or they don't ward jungle entrances, or are terrible at kiting, but he basically just becomes a counter-jungle when it does happen, and he is at best an even trade with the big 4 junglers (kha, lee, elise, and eve) if they ever meet up.
Not saying he's bad, as his clear time is still god-tier, but he's more one dimensional than xin when it comes to jungle ganks.