Few things:
-I don't think we were really that bad of a team last year, we had some awful games (Juve & PSG) and Lucho made stupid rotations but we lost like 8 points out of last 21 games IIRC. but we reached a point that we were tactically inept and lost motivation. that needed to stop and Lucho knew he wasn't the guy to do it and stepped out of the way.
-We took a step back rather than a step forward this summer, we lost our second best player, got a young prospect in Dembele who got injured (and I doubt he will be anything close to Neymar anytime soon btw,kid has long way to go) and we didn't address many of our problems, in fact we remained reactive rather than proactive and didn't foresee the drop in Suarez & Pique form. Never mind failing to get rid of unwanted players like Vermaelen and Arda
As for EV:
-Our form leaves a lot to be desired, I think that is a fact so far. We aren't dominant or the team that everyone fear. he has been over using the likes of Rakitic & Iniesta, might argue that Suarez,Messi(with his age, he will need to start resting sooner or later) & Pique too.
-That said, there is also many positive stuff :
1-Bringing Messi back as false 9 has stopped making Messi a tactical problem himself and made us having a right side again, Suarez isn't a LW but he stays more on the left side than Messi did before on the RW which keep the opponent LB occupied and left things open for Alba
2-There is overall more balance within the team , and even with Pique shit form we are better on the defense
3-The team has been also improving from inside, S.Roberto is in better shape,Denis is doing better, even Gomes isn't as shit as last year if we are gonna be fair
4-All of our four new players are adding something new to the team, Gerard is giving us a true quick winger, Paulinho giving us a true b2b midfielder ,Semedo is a natural RB who is solid in defense and Dembele give us creativity. That can't be said in any of our transfer market since 2013 (because we only bought Neymar) and I think EV has a role in that.
-There is also some other debatable issues,not using youth (I think he was in no position to give Alena playing time up till now) or giving Semedo more time (but you can argue Roberto hss been really solid) etc
So overall I think it is a bit too early to make a final conclusion, EV is surely bringing something tactically to the team, but he also doesn't bring excitement