Dont disagree on Patel, all I'm seeing I can see the minuscule logic as to why they might have gone for Patel as replacement.
One thing we got to cognizant about is that ENGs biggest challenge on this tour won't be the overall strength of the bowling, because as you might on previous trips to UAE/India/Sri Lanka circa 2012-2013, the quicks and spinners did well. Its the batting that crumbles - so if the scenario did arise where ENG feel they got pick 3 spinners in one tests, Patel's extra batting ability could come in handy.
No doubt its a hunch/risk selection either way.
If the recent NZ vs PAK test in Sharjah which is hosting the 3rd tests of this tour is any indication to go by, England might very well and be faced with a situation where they have to seriously consider playing 3 spinners. NZ brought Vettori out of test retirement to partner Mark Craig/Ish Sodhi just to play that test because it was such a dustbowl -
3rd Test: New Zealand v Pakistan at Sharjah, Nov 26-30, 2014 | Cricket Scorecard | ESPN Cricinfo
This is where i think Ansari was being penciled to play and why as aforementioned am seeing the small logical reasons why i think selectors picked Patel.
Also i might add, i think Finn & Wood given their natural ability to reverse swing the ball should play in all 3 tests & realistically one of Anderson/Broad should play.
Anderson 13 wickets at 15.61.
Anderson and Broad are England's best bowlers, why would you have left one of them out. Don't you think Anderson can reverse swing the ball? He has got hundreds of wickets doing just that.
We should have played 4 fast bowlers and Ali.
Seam - 31 wickets at 24.58 econ 2.29
Spin - 20 wickets at 59.85 econ 4.07