That kind of sounds Sheepish. First off, Dr. Mundo is a sustained damage tank. He is never scary unless you're hit by a Cleaver and have no way to escape. Mundo gains 100 AD, potentially gaining another 99 based on his health. It has no scaling, he has no AA reset, and he has one of the lowest attack speeds in the game. He will only get 2 attacks off in 5 seconds. Mundo's only option is to build tank because he doesn't do well building anything else.
1 Total AD + 199 (at 1% health)
Yorick gets an AA reset which can be done in less than 1 sec.
1 Total AD + 1.2 Total AD + 150 + [40 + 35% Total AD (per hit by ghoul)]
Mundo gets a 35% speed boost when he ults. Yorick gets a 35% speed boost by pressing Q. The duration is 5 seconds, his cooldown is 5 sec with no CDR. Meaning he can ALWAYS have his speed boost up and AA reset often versus Mundo's 7 second CD.
Mundo's Slow is 40% and last 2 seconds, dealing 280 dmg to a single person, but does scale if versus tanks.
Yorick has a 40% AoE slow, lasts 1.5 secs, and whenever his ghoul (40 + 35% AD dmg per hit) attacks, it also slows for 5 seconds. It also gives sight.
Yes Mundo is a better tank, that's what he does. But his damage is not scary. The only scary thing about Mundo is that if he lands a slow on you, you might be stuck fighting him. He has CC mitigation but no damage mitigation, so he still suffers horribly to ADC.
Yorick gets 20% damage reduction, technically has 4 damage abilities, and heals 40% of all damage his E ever does whether it be immediately or sustained. Yorick can fight an ADC with his burst (since honestly they will always win a long duration trade).
In 1 Second, spam blasting his ghouls. He can deal, after 1 autoattack:
121 (auto) + 121 + 150 (120% AD) + 200 (100% AP) + 175 (100% Bonus AD) = 767 + 145 = 912 + AP + Bonus AD
1 Attack from every ghoul = 180% AD + 40 = 258
===> In 1 second, Yorick deals **1170 **base damage.
Mundo deals **689 **damage in 1 sec at 1% health. He does 59% as much damage, and his sustained damage is mainly his W with an AP scaling, while Yorick's is 105% Total AD + 40 per second. Yorick is very scary. Not to mention his itemization strongly benefits his damage and sustain while Mundo's itemization only really benefits his sustain.