Sevilla are a frustrating team, they're so nearly good. Navas has to be the definition of an, "on his day," player - he can be so good some weeks. You have to wonder what kind of player he'd have been if he'd been able to get over the homesickness and fear of travel.
Yeah it's mind-boggling how Sevilla can be so inconsistent, but then that's a criticism you could level at a lot of Liga teams on the brink of European places, IMO the competition is really fierce between places 5-15 and away games are always a stumbling block for any team outside the "big two" (just look at Atlético's home/away record this season!)
home: 12 played, 12W (!), 0D, 0L; 33 GF, 6 GA (!!) (+27); 36/36 pts
away: 11 played, 4W, 2D, 5L; 11 GF (!!), 17 GA (-6); 14/33 pts
They've a perfect home record, 1st ahead of Barça and RM, and are only 6th in away record, behind (in order) Barça, Betis, Málaga, RM and Valencia.
Curiously Betis have the 2nd best away record with a negative goal difference
courtesy of getting thumped 5-1 in the Seville derby, I presume?
Re: Navas, he was consistently outstanding in the period 2007-2010 with decent end product as well. I haven't really been following them the past 2-3 seasons, but I guess their major problem is with the holding mids and central MF in general? They used to have Zokora and Romaric who started out brightly but didn't last too long, then they had some failed transfers in Cigarini and Guarente and I really thought when they got Medel and Rakitic they would get back to their pre-Guardiola state but it hasn't quite happened. That Kondogbia fellow seems a good prospect from what little I've seen of him and at a very young age as well.
Another thing to note is how Sevilla have perennially bottled European games ever since their back-to-back UEFA Cup wins, their results and performances getting increasingly worse. Starting with defeat to an (admittedly strong) Fenerbahce on penalties in 2008 CL round of 16; followed up by a ridiculous 1-2 home defeat after getting a good 1-1 result in the 1st leg against CSKA (2010 CL, R16); and then getting beaten by Braga in a CL playoff in 2011 and by Mönchengladbach in a qualifying game for the EL in 2012... Somewhere in between there was getting eliminated in the UEFA Cup group stage in '09. Quite a downfall since 2007. I'm guessing Palop and Navas are the only ones left from those days? (Fazio was in the youth system back then if I recall, and he also hasn't really turned out as expected).