Kind of missed out on putting out a 25th Anniversary game of Blood Bowl last year. The Internet was certain that they would. ...And then they didn't. Instead their 'big, exciting release' for December was a pun on 'big'. Ergh.
Depends what Eldar list they're running. Wave Serpents are completely different to Jetbikes/Hyrbrid are completely different to Footdar.
But, your winners are going to be;
Hellhounds
Leman Russ Eradicators
Colossi
Hydras (for Wave Serpents and Jetbikes)
In case you didn't spot it, Eldar are all about the Cover Saves. Then, just in case of Wraithknights, you need to bring Vendettas and Ratlings (I swear by my Ratlings, but, they're not for everyone...For those people; Marbo). Plasma Commands aren't going to work as well either. So, break out your Meltaguns and Meltavets again from 5th Ed. and rumble them forward. As always, your goal is to smash anything that even looks like it has a Bright Lance - or is a Wraithknight - and then try and kill some Infantry.
A typical Eldar list has a lot of S6 and S7. But not a lot above that. So, any Leman Russ will do. Except the Punisher - which does nothing - and the Executioner - which is just expensive, and Eldar don't have 2+ Saves anyway outside of Protected Jetbikes.
Yeah, it's better. But it's still the same pitfall. It doesn't actually hurt a balanced Codex with good choices (Tau, Eldar, Marines, Daemons), and the Codecies that it does hurt, hurts a whole lot worse.