Wanderers had a host of players missing last weekend when they went down 1-0 at Blackburn, with the likes of Gretar Steinsson, Sam Ricketts, Stuart Holden, Mark Davies and Daniel Sturridge all sidelined by injury.
Knight cannot fault the efforts of those who have deputised but believes Coyle will need to reinforce the group with new signings in preparation for next season.
"We haven't got the biggest squad but the players who have come in have tried hard," said Knight, quoted in the Bolton News.
"That's one thing we have got here, heart. But we do have to add to it as well. You can't just rely on heart, we need depth as well."
Source: PA
Source: PA