The forwards were left out of Neil Lennon’s starting line-up in Saturday’s Old Firm defeat but featured as second-half substitutes. Rangers won with two goals from defender Connor Goldson.
Defender Ross, who left Ibrox in 2005 was shocked by the Celtic line-up against his former side, and asked why the key strikers were missing.
Speaking on BBC Sportsound Ross, now coach at Motherwell, said: “Leigh Griffiths is struggling for fitness? How long does he take to get fit that boy, and Ajeti?
“It takes six weeks to get fully fit, pre-season usually takes four weeks. We’re four months into it now - how can you not be fit? What are you doing day to day?”
Ajeti has scored five times in 10 appearances, but started just three times and is yet to complete 90 minutes. Griffiths came off the bench to score at St Johnstone last week.