The Hammers were busy during this summer's transfer window, with manager Sam Allardyce bringing in nine new players.
Downing believes that a fuller squad at Upton Park can only be a positive for West Ham as they look to improve on last season's 13th-place finish in the Premier League table
"Competition for places is definitely a good thing. Last year even if you weren't playing well you got into the team because we didn't have enough players, but now the manager will be having headaches picking the team. I'm sure he'll like that," he told the club's official website.
"We've got more options on the bench. We've got Kevin Nolan and Andy Carroll to come back still. The manager has said before, the team picks itself. If you're doing well you'll stay in the team and if not then you'll be out."
West Ham return to action on Saturday when they travel to Manchester United in the Premier League.