I think it's hard to tell from what's happened so far, due to the lack of quality opposition. You can only beat what's in front of you, of course and they've largely done that, barring Sevilla. Barca don't look particularly good though and Girona top the league, so it's an odd one.
They have four slots and those were filled by Barca, Real, Atletico and Sociedad. Sevilla finished 12th in La Liga, but won the Europa League and qualified due to that. West Ham did something similar in winning the Conference, but finishing 14th.
(Belated) CL last 16 draw : Porto v Arsenal Napoli v Barcelona Paris St-Germain v Real Sociedad Inter Milan v Atletico Madrid PSV Eindhoven v Borussia Dortmund Lazio v Bayern Munich Copenhagen v Manchester City RB Leipzig v Real Madrid Porto to renew Wenger era CL KO stages for them lot ?? Other than that, no real potential shockers IMHO.
CL draws ... QF : Q1 - Arsenal v Bayern Munich Q2 - Atletico Madrid v Borussia Dortmund Q3 - Real Madrid v Manchester City Q4 - Paris St-Germain v Barcelona SF : S1 - winner of Q1 vs winner of Q3 S2 - winner of Q2 vs winner of Q4
EL draws ... QF : Q1 - AC Milan v Roma Q2 - Liverpool v Atalanta Q3 - Bayer Leverkusen v West Ham Q4 - Benfica v Marseille SF : S1 - winner of Q1 vs winner of Q3 S2 - winner of Q2 vs winner of Q4
EL2 draws ... QF : Q1 - Club Bruges v PAOK Q2 - Olympiakos v Fenerbahce Q3 - Aston Villa v Lille Q4 - Viktoria Plzen v Fiorentina SF : S1 - winner of Q1 vs winner of Q4 S2 - winner of Q2 vs winner of Q3