Jtp - I missed your post until this just got bumped. I'll respond to it and we'll see if you come back to defend your absurd position. I'll use your numbers, since it's pretty obvious you didn't bother actually doing the math:
Ok, so Heyward has one error every 82 chances. In his last season with the Braves, he had a range factor of 2.56 chances/9 innings. The 2 years before that, it was more like 2.3, so let's split the difference a little and say he gets to 2.4 balls/9. Now let's say you play about 1300 innings. That's a little low, but in the normal range - about 145 or 150 games worth of defense. So based on that range factor, in 1300 innings, Heyward gets to 347 balls. One error per 82 chances means about 4 errors, so he makes 343 outs.
On the same team, the very next season, Markakis put up a range factor of 2.02. So in 1300 innings, he gets to 292 balls. One error per 162 chances gives him only 1 or 2 errors. So let's give him credit for 291 outs.
Now, you want to talk about arm. The tangible result of throwing arm is outfield assists. In 2014, Heyward had 10 of 'em. In 2015, on the same team, Markakis had 4 in more innings. So add in those extra 6 outs and Heyward is making 58 more outs per season. Again, this is using YOUR numbers. So your argument is that "most" would take player B. I'd say the contracts of players A and B beg to differ. Most would take A. And unless you're arguing that the value in preventing runner advancement of Markakis' arm is worth more than 58 outs, "most" would be right, and you would be wrong.
58 outs is 19 innings. That's more than 9 runs worth of advantage. I don't think the arms are all that different, either. And, by the way, if you look just MARGINALLY deeper, you'd find that Heyward made 6 errors in 2010, 6 in 2011, 5 in 2012, and 4 total in the past 3 seasons combined. Which is more than Markakis made in the same 3 years (1). But that 1 extra out given back per season is probably not very important relative to the extra 60 balls per year he's getting to.
I don't think the arms are as different as you think, either.