@chibob - I lost the original post and thread where you were wondering about why people don't think Ospina is all that good. I'll just respond in here.
Ospina is a very good shot stopper, but I don't think he's an elite goalie. I'd put him a notch below that, probably similar to a Guzan/Howard/Forster level. Above average shot stopper, good decision maker, weak everywhere else. His problem is that he's not very good anything else for a goalie. He's short (6 foot at most), which means he has troubling dealing with crosses. He can't claim them with authority. He doesn't command the box all that well (and Szczesny is actually pretty good at that, excepting when he decides to go crazy). His kicking is terrible. He has trouble getting goal kicks over the halfway line. I'm not all that confident in his handling, after he bungled two easy shots in the last game of the season for Arsenal. Those things are really what separate someone like Neuer from other shot stoppers. Ospina is a good goalie, but he's not elite.
And I think all this stuff is important for Arsenal, because their defensive organization can be really bad. A good goalie can really help with that. Lehmann was very good at that at the beginning with Arsenal, hence his big shutout streak in the Champions League when Arsenal was starting Senderos and Djourou. That's why I think Arsenal needed an upgrade at goalie more than anything else for their defense. I don't think Ospina saved them many points this year - their defense got better in the second half, but that's also when Mertesacker and Koscielny were healthy and playing together almost every game. Ospina didn't cost Arsenal points, but I really don't think he gained them any either.
Could Arsenal win the league with Ospina in goal? Yeah, sure. But Cech helps them a lot more than Ospina does in my opinion.
Plus, Cech is better rated in FIFA than Ospina is