The club's sale of the 30-year-old was tempered by the fact the Hammers signed Marseille star playmaker Dimitri Payet who was one of the best players in the Premier League this season until his injury last month.
The creative midfielder was making all the headlines last season but is living a lower profile existence now.
'I may regret it'
He is clearly enjoying life back at his boyhood club but admitted in an interview with the Telegraph he may yet live to regret his decision to leave East London.
"I’ve had no regrets up till now.
"We’re in a good position in the league and after tomorrow night we could be in the semi-final of the cup.
“The aim is to get promoted, but this is a great opportunity for us to reach a semi-final. By the end of the week we could be top of the Championship and looking forward to a semi-final."
Midfielder would have faced challenge to keep his place at West Ham
In truth Downing would have been under pressure to keep his place in the West Ham side under Slaven Bilic because the Hammers were one of the busiest Premier League clubs in the summer transfer market.
Co-owners David Sullivan and David Gold were true to their word by investing significant funds to strengthen Bilic's squad.
Payet has very much taken on the role Downing assumed last season and is considered one of the best players in the club's recent history.
He would undoubtedly have found himself in the side at the moment, though, given West Ham's seemingly annual injury crisis.
But should he lead hometown club Boro to promotion his decision could well be vindicated.