Thomas (concussion) was estimated to be a non-participant at Monday's walkthrough, Rich Cimini of ESPN.com reports.
Thomas suffered a concussion in Sunday's 27-20 win over the Browns, so his absence Monday comes as no surprise. The cornerback is facing an uphill battle to play in Thursday night's contest against the Patriots, and if he's unavailable, Qwan'tez Stiggers would be a candidate to see an increase in workload in New York's secondary.