Home/away breakdown for batsmen to me only matters in the sense of someone playing a disproportionate amount of their games at home or away from home. If you're playing 60% of your games at home then you're going to have an advantage, as playing at home is typically easier for most players.
I totally reject the notion that someone who averages 50 at home and 50 away is somehow better than someone else who averages 70 at home and 35 away (assuming all other things equal of course) just because he apparently conquered all surfaces. I do actually think it's a bit different for bowlers because bowling works so much differently to batting, but as a batsman you're going to have your good games and your bad games regardless; if your good games group together at home to the point that you're absurdly good there then you can absolutely make up for a 'poor' away record. Roughly half a player's games will be at home afterall, so while away Tests may be a 'better test of skill' or however you want to spin it, they're not intrinsically more important.
I agree with the core of what you're saying, (ie) home runs are too often brushed aside by stats-pickers. But you're exaggerating it a bit there. I don't know if it's the same mentality for you guys, but for me, there is zero doubt that runs overseas carry more weight than those made at home. We've always been a ****house cricketing nation for most of our cricket history, primarily because we didn't at any point in our history have cricketers who could adjust to overseas conditions. It is absolutely no coincidence that we started winning tests overseas once we got guys Tendulkar, Dravid, Laxman all performing overseas. Overseas victories and overseas runs are rarer, more cherished and hence, more valuable.
And a 50-50 average definitely is more valuable for me. I'd have both those batsmen in the team, but one is more likely to score runs no matter what the conditions are. Home bullies are not really a rare species and that 70 average at home doesn't have nearly as much actual value as an away average of 50 because the other batsmen are
generally more likely to score a decent number of runs at home anyway. In terms of actual utility, on average, there will not be that many batsmen in the team who'll be able to stand up and score runs in overseas conditions, and hence, the one guy who does average 50 overseas becomes a massive asset.
There's a reason we have more home track bullies than overseas bullies like, say, Mohinder Amarnath. As I said, I'd have both in the team, but being an HTB is easier and less valuable.
