Well, I think they signed Kendrick to play LF. I also don't think they realized they would have the opportunity, or the interest, in signing another vet to play RF at the time they acquired Kendrick (which was before Hellickson accepted his QO too). I think we would have seen Nava, Altherr and whoever else (including Quinn) in RF. I think ownership's goals changed, and so did the market. I also think they decided to sign Herrera because they could no longer feel like Altherr or Quinn was going to displace him from CF..
Anyway, I don't really have an opinion about this stuff, I just think this is what the Phillies are doing. Quinn's chances of making the roster are slim, and that's even with the 40-man crunch. He hasn't played in the bigs enough to prove he can hit ML pitching and there aren't enough ABs for him to prove that in the first half of this season either. Technically the same is true of Altherr, he hasn't done it for very long or showed he's healthy yet.
I would agree Kendrick is the expendable one, though you'd want to move Saunders to LF I'd think. But, like it or not, sunk cost or not, Mackanin was promised his veteran bats/leaders, the GM agreed that's what the line-up needed, and on top of that Klentak has a strong connection to Kendrick.
I'd be just as happy to watch a team with no Bucholz, Saunders or Kendrick myself, whether it would be better or worse than one with Eflin, Altherr and Quinn doesn't really matter. So either the Phillies are foolishly chasing short-term wins with those vets, or they truly believe it's not in Altherr and Quinn's best interests to be everyday major league starters right away (ditto Williams and Crawford obviously).