Not sure what Lazio you have been watching, but having seen games like their Viola one, Lazio are anything but boring. They have a quite silky and exciting attacking players who play quite nifty counterattack football (scored much more then others so far in the league).
Its us who are more likely to be boring really.
And Zarate, even though too much of a ballhogg, can make it anywhere, he is a sick talent. And Lazio in general, I believe they will threaten Viola ALOT, Viola will be yet another team who doesnt have the squad to handle both CL and league at the same time, so they will have a bit weaker league season this IMO. A team like Lazio who can only concentrate on the league and have this kind of attack can pounce on that. But doesnt mean Top 4 though, for them to be top 4, Milan has to be way crappy then usual to miss top 4 this season too.