A person from my group found out an inconsistency regarding the Weretiger template in the 5E Monster Manual page 207. It describes the animal and the hybrid form to grow to enormous size (the same is stated above for the werebear) but later on on the table of the werebear we see that it describes their shapechange like this:
The werebear can use its action to polymorph into a Large bear-humanoid hybrid or into a Large bear, or back into its true form, which is humanoid. Its statistics, other than its size and AC, are the same in each form.
Whereas the Weretiger table gets this:
The weretiger can use its action to polymorph into a tiger-humanoid hybrid or into a tiger, or back into its true form, which is humanoid. Its statistics, other than its size, are the same in each form.
In the table of the Weretiger we see no mention of growing to enormous size (large) and also in the table it mentions that all statistics remain the same except its size… but wait there is no mention to the size changing… How can it be?
So here is my question.
Is it possible that the developers forgot to add the word Large tiger-humanoid hybrid and Large tiger ?
If it turns out to be true what me and my group found, then we found something that should get into the next errata.
Best Answer
If you flip to page 339 of the Monster Manual, you can see that tigers are Large creatures. There are several different varieties of bear, some of which are Medium, some of which are Large. So the Werebear had to specify that its bear form is a Large creature, but the Weretiger's tiger form will logically be Large.
Note that the Wererat's Shapechanger trait also mentions that its size changes, and doesn't include a size keyword, which is because the Wererat transforms into a giant rat, a small creature. So that's nice and consistent.
The remaining (less consistent) question is whether the Weretiger's hybrid form is Large. Given that the description of the Weretiger says that it grows to enormous size in its hybrid and animal forms, (the same wording as the Werebear, which none of the other lycanthropes have), it seems reasonable that the Weretiger's hybrid form is also Large.
It certainly seems possible (even likely) that the writers forgot to add the Large keyword to the Weretiger's Shapechanger trait, but ultimately, it's up to you to decide whether you want the Weretiger's hybrid form to be Large or Medium.