I think you missed my premise, which was that Bohm ends up being dealt. I wasn't recommending that he should be traded and replaced by Arenado. I was just commenting on what the Phillies could do at 3B if they have already traded him, presumably for something else of value (perhaps pitching).
If Bohm is traded, the Phillies need someone to play 3B. I think Arenado--again, if they don't have to give up much to get him--is a reasonable replacement. He probably isn't Bohm's equal on offense at this point (though Bohm could certainly backslide), but Arenado provides value offensively and defensively.
The question of whether the offense has gotten better should be made based on my original premise--that Bohm has been traded. Is Arenado better than the in-house alternatives (Sosa, Clemens, Wilson, etc.)? I'd say yes. And clearly there is an improvement on defense.
It's not a question of whether the Phillies can afford Arenado. They can, even if they have to pay most of his salary though they might choose not to make that investment to avoid luxury tax increases.
