Ashwin and Jadeja are allrounders and capable of adding extra 40-50 runs on the scorecards together. Extra 50 runs down the order matters when you're up against the quality bowling lineup in case of any batting collapse. Let's see what happens.
I agree on Jadeja, but Ashwin hasn't scored enough runs in SENA countries to get elevated to the "allrounder" category. But he is quite capable of building a partnership that can add 40-50 runs to the total. The question is whether they need two spinners, when the curator himself has said that the pitch is going to offer a lot of assistance to the pace bowlers. And Ashwin is someone who has historically performed poorly under such conditions. And among the pace bowlers, Siraj is the only one who has some batting capability.
Don't know if you follow Test cricket or not but since 2018 he's performing quite well with the bat in the SENA countries.
He's number 8 batsman and bowling all rounder so ofc he won't score 50 or 100 regularly like other batsmen or batting all rounders but he has 5 test tons under his belt. He did fairly good job in SA with couple of 30s +7 wickets in 2 games and don't forget recent match saving inning in Sydney + 12 wickets in 3 games. In last English tour his average was like 25 ish with the bat and took 11 wickets in 4 games, didn't bowl single bowl in 1 match because pacer finished the job, this seems good all round performance to me tbh.
If he manage to get 4 wickets and contribute 30-40 runs when batting at number 8 then would say it job well done, failure is part of the game, which can happen anytime but its fine too because atm he seems best bet for India considering his confidence is high due to recent success.