By the sounds of it, it doesn't sound like a bad idea to play four seamers judging by the pitch report which says that there is still some grass on the pitch as of now. Glad Thakur and Siraj are playing, excited to see how they go about it. Would've preferred Ashwin as he is a superior spinner compared to Jaddu but his batting overseas hasn't been great compared to Jaddu. Looks like the spinner will be playing a more defensive, holding role, which Jadeja can do well.
On the other hand, it looks more and more likely that England will opt for an all pace attack for the Ashes considering how little game time they're giving their spinners in Test matches.