Yup. It's almost entirely destroyed Barça's tiki-taka through the middle. I love Messi, but building tactics around him as a static CF (or false 9 with no one in front of him) makes it impossible to create with triangles through the middle. Which is why I enjoy Spain more, at present: it's Barça with a stronger defense, more fluid forwards, and no Alves crosses.
I know Messi hasn't been too mobile in recent times but that's hardly the source of why our system can't be played (I believe it's more of an effect). As much as I liked him as a person, that was really down to Tata being incapable of instilling tactical discipline into the side.
All of our players were given free reign to do as they pleased which resulted in scattered positioning, sluggish tempo, and individuals pretty much choosing their own instruction (Messi walking, Alves crossing, etc.). You couldn't find a proper link between multiple players, 2-3 at a time were walking while others made out of place runs. No cohesion, no play as a unit, and a majority of our buildup came down the wing resulting in an Alves cross. Usually we committed maybe 3 players in the middle of the 7 defender body inside the box waiting to receive the cross as well while only guys like Iniesta/Xavi/Alves stay on the outside unsuccessfully trying to find a way through before crossing it. It's ridiculously un-Barca like. We looked closer to current United than Prime Barca many times given the way we played.
A proper Barcelona side is much more disciplined. The positioning and distance of the players is purposeful and coordinated to create those links and triangles that allow us to play through the middle with the technical wizards. Then it frees up the wings for the likes of Neymar/Alexis to make a piercing diagonal run that can result in an attacking move.
Look at how balanced the positioning is and how proper the team shape looks, namely because everyone's movement is with complete regard and awareness to where the ball is and how to provide a connection between multiple players. The triangles we created with that kind of movement gave us a clear path at goal and true domination rather than passive possession. Our team now doesn't have 1/2 of this amount of movement and it's completely scattered. Prime Barca was organized and diligent, a far cry from what we've become now.
Our players might have talent but they desperately need a coach that clearly is in charge of what they do. Guys like Messi and Alves showed their worst sides when not under proper instruction. The way we've fallen as a team has manifested itself on Xavi too (who CAN do a lot better with less over-playing and a better team around him). For me, Messi not moving as much isn't the true problem for Xavi's decline because the true issue reflects on a much bigger picture which is the result of our decline as a collective.
In short: Messi could be running like a dog but it still wouldn't improve Xavi's game much unless the entire system is fixed.
