She's not Quicksilver. Logan has managed to hit acrobatic/quick opponents before. She's also not Wasp, so it's not her size that's would make her hard to hit (hell, I think she might be a little TALLER than Logan).
She might be fast but logan always has held back in comics when sparring with others who aren't as sturdy as him. Even without his claws that skeleton of his would be like getting hit by a truck.
So, your dislike for Squirrel Girl isn't the concept of the character but the portrayal of the character in a F2P MMO? No one can blame you for being soured by the portrayal of Squirrel Girl in that MMO, I was completely soured to every character... bad MMOs can do that.
There isn't much to understand about the character, Squirrel Girl was meant to be a Lighthearted escape from the sober X-men series of the early 90s. In 2005 Dan Slott repurposed the character of Squirrel Girl in his Great Lakes Avengers series; if you haven't read Great Lakes Avengers, read it. It's a lot of fun. More recently writers of "New Avengers" have used Squirrel Girl as a super powered Nanny. She's a fun, nutty character (pun intended) much like Dead Pool.