2 years ago he anchored a US 4x1 at World Relays and beat Usain Bolt. He was clocked in that race by US biomechanist at faster than anyone in the relay except Bolt who was slightly faster. Gatlin was in the race and he just won the World title in 100.
Bailey suffered a hamstring injury prior to that race, reinjured it there and then still ran 9.93 with awful start in Jamaica while coming back hard vs Asafa Powell but further damaging his hammy. After a year of treatment and therapy it still wasn't healed. The opportunity to try bobsled was there and it turned out pushing the sled has proved great therapy for his injury. He has pushed with top US sled in practice and broken all the push trial time records while not fully healthy or fit.
He recently said he plans a return to the track in 2018 after the Winter Olympics so we will see if again is a force on the track. Certainly his weight is a major issue as it is for any athlete trying to run under 10 seconds as every extra pound creates demand for 3 times the force to move that weight.