Gotta agree. I wasn't really watching many games the past 2 seasons, partially because I didn't have as much time, but also because everything around the club has became so stale. Same playstyle, same mistakes every year. You could easily predict how CL is going to go - matches against weaker opponents are gonna be lost, that is going to result in a 2nd place in groups, tough opponent in first knockout round, terrible play in the first leg, improved performance in the 2nd but not enough to go through.
That is pretty much has most of the last 5-6 CL campaigns went.
Switch to a different formation and Lacazette's signing got me atleast a bit excited about the club again, and first game confirms it.
Re: CB's - I am not worried about this position really. There are 4 CB's (Gabriel, Kos, Mustafi, Mertesacker) ahead in the pecking order compared to who was on the field tonight (bar Kolasinac I guess, I am not sure where is he going to play, in Schalke he used to play LWB/LM when they played with 3 at the back). 4 CB's were signed in the last 3 seasons - Mustafi, Holding, Gabriel, Chambers. If anything this position needs an overhaul, decide who sign and who to sell, but not just keep signing CB's.