They have been playing well no doubt as they are still in the hunt for CL and UEFA.  The 3-0 at Fiorentina and the 3-3 comeback from Udinese showed strength but Inter 3-0 , Milan 4-1 and Juve 1-1 were not great.  These are the games that can have the greatest impact because for most teams they are writeoffs.  If you watch some if the low ranking teams this season against the bigger clubs there have been some extremely close games and teams like Atalanta, Siena, Cagliari have caused alot of problems for them for 90 minutes.  That is all that Lazio have lacked against these bigger clubs a full 90 minutes of quality play.