Pop won't certainly go after him telling "we want you to play like you did last year". He would tell him that they will ask from him to try more defensively and to be more team oriented offensively. If Beasley isn't fine with that, then he wouldn't sign with Spurs. If Beasley agrees to change his game but it didn't work out for some reasons, Spurs could easily waive him. Anyway, let's see first if Suns waive Beasley.
Regarding the chemistry, I find it's important for Spurs to start this season with a new hope after the heartbreaking loss last year. Spurs have already tweak a little their team with Belinelli and Pendergraph and some players like Leonard, Joseph, De Colo or Baynes might have a bigger impact, but I doubt it's enough. If Spurs players were in the mindset "we look better than last season", it certainly would help them to start with a fresh mind and not being stuck on last season huge disappointment. That's a reason why I was so hard on Spurs FO for not getting Kirilenko, Spurs really needs some new blood to start battling again for a le. I don't want the 2013 run being remember as Duncan's wonderful but very cruel swan song.