Not sure your account holds that much water here.
Batting - the fact is that his batting average last season is 11 a knock lower (and is inflated by cheap runs against the UCCE that Rashid did not get the opportunity to score) and five runs a pop lower over the course of the two men's respective careers. You site environment but he played a maximum of half his knocks at Chester-le-Street (which is nowhere near the green seamer that it is reputed to be once spring passes - check the average first innings totals). At worst, Rashid is as good - I think anyone who has seen the two bat would say that he is comfortably the better player.
But it is the bowling that is the biggest difference. Whilst their raw figures were similar last year, those numbers do not reflect in full the different roles in which their respective sides used them - Borthwick was given a couple of overs against the tail which allowed the odd cheap wicket, whereas Rashid was asked to bowl sides out in the second dig or to hold up an end on some of the mid season Headingley roads. As such, RAshid was exceptional value for the numbers when compared with Borthwick. I would also point out that Borthwick has never really been a frontline spinner - he has only taken two five wicket hauls in 60 first class matches, compared with Rashid who has taken 17 in 115. I challenge anyone to look at those figures and say that Borthwick is the more likely to take wickets in Test cricket!
As I've already stated I haven't included any UCCE games in this, all CCD1 stats. I'd disagree completely about the Riverside wicket, ask any player, there isn't a more difficult place to bat in the country, possibly Trent Bridge when overhead conditions are favourable. I've seen both bat live and in my opinion Borthwick looks a more compact and relaxed batsman.
You stated earlier where is this spinner friendly wicket both Headingley and Scarbs offer considerably more turn than the Riverside, do you agree? That's a fair enough point about the different roles they play, however there is not much you can do when you have the best pace attack in the country blowing teams away. Obviously Rashid never bowled against the tail and took a cheap wicket, so can't see your argument there. I was at Scarbs when Durham beat Yorkshire and Borthwick comfortably out bowled Rashid, on a surface which offered a bit to the spinner maybe this is why he was picked ahead of Rashid?
Agree totally about Borthwick not running through teams but what I would say is he has to bowl after Onions, Rushworth, Thorpe, Wood, Claydon, Brathwaite and Harrison, after that let's be honest there's not gonna be too many wickets left to take? Rashid as you say bowls a lot more therefore is likely to take more wickets, Borthwick will probably bowl more for England than he does Durham!