Hi,
first of all: i suck (my english and my lol-skills) and i didnt played lol S3. So this is basically theory. I used to play Udyr a lot in S1 and S2 and i noticed that he fell off extremly in S3 - so i tried to figure out what is new role and build might be.
Role.
So Udyr just suck as a tank and kind of as a Bruiser, because he can be kited easiely - like you saw him in Gambit Gaming using it, he was useless in teamfights! So his role cant be to interrupt AD or AP carry, or to initiate. His new role might be to eat high HP targets. (If you can get to an AD or AP carry and stun them you´ll do fine anyways, but most of all you will get kited and eat a lot of damage for nothing)
The Build.
So i figured out what the build of udyr might be. As a Top-Laner he kind of sucks, because Tiger just falls off vs. other AD bruisers - so i still try to go the Phoenix Jungle way.
High HP Targets like Bruisers tend to stack a lot of armor nowadays. And Phoenix does a lot of magical damage + there are some nice itmes for that niche. So let me try this:
liandry's torment might be a very good item for udyr. while is R ticks 5 times and liandrys got a 0,5sec resett you should get 10x the liandrys effect. + if the target is slowed its doubled, which is a nice bonuus for udyr! Dont get me wrong, AP is terrible on udyr, he doesnt scale well at all, but the passiv of liandrys might be worth a try + the extra magic pen leaves room for more tricks.
wits end. synergies perfectly with magic dmg and liandrys. you do more basic attacks which deal more magic dmg, so liandrys triggers more often + phoenix 3 hits trigger more often. + wits end itself deals magic dmg.
randuins omen. is kind of a standard item for me on udyr - you get a lot of health + its synergies with the slow effect - double liandrys passiv!
sunfire cape. is a great item overall, even for AD bruisers - so if you got some extra magic pen, this should be great. + extra magic damage from the passiv.
(so is the core, there are a lot of other viable options but thats just the idea. 'The new Blade of the Ruind King is a variable option because of the slow + extra HP based dmg + IAS - but its dealing basically physical dmg.)
So i checked out Diamondprox udyr runes: and he runes +flat dmg marks, +flat armor seals, +flat/scaling mr glyphs, +MS Quints - so why not replacing the marks with +flat magic pen marks - if someone could test the jungle times: dmg marks vs. magic pen marks vs. magic pen marks - would be great.
Masteries should be 0/21/9 standard for udyr - or if you really want to go for damage 9/21/0 +AS, +%Magic Pen - sounds kind of nice.
So again: this is theory, i cant test it, but it looks interesting on paper. Whats your oppionion?

I play Udyr totally normal at either top or mid and it is totally viable.

I used to play Udyr a lot in S1 and S2 and i noticed that he fell off extremly in S3 - so i tried to figure out what is new role and build might be.

Just check: http://www.reignofgaming.net/tier-lists/jungle-tier-list/22968-jungle-tier-list-thresh-era - he used to be top tier 1, now hes bottom tier 3

Well, yea. It's because counter-jungling isn't as strong, all the 'good' junglers can out-duel him and he doesn't have a reliable gap closer other than running at thm.
Compare that to Xin who has a dash+slow, a knockup, AoE knockback, AS buff, self-heal and an autoattack reset.
Now look at Udyr. AS buff, shield, stun, DoT, MS boost, AoE. Of course, the stun, DoT, and AoE damage all have to be done at melee range with no reliable way to get there. While Xin has to be in melee range too, he has his dash to help him get there.

Thats why i hope he gets a new role - not initiate or AD/AP Carry CC´er. Eat up High HP Targets, Eat up bruisers - i dont think Xin can outbattle him with this build.

What lol no. is still very strong in the right situations and even if he wasn't you're not gonna make him better by getting on him xD. However AP can be a fun troll build. , , , , and other tank items. Pretty fun stuff lol.