The black, green and gold only had one senior lock in the 29-man squad, with flanker Tom Wood forced to fill in alongside Alex Moon.
Saints were shorn of several key men for various different reasons.
And Boyd said: "We've got Karl Wilkins and Dave Ribbans finishing off suspensions from last year so we had those two boys unavailable.
"Then we had (Api) Ratuniyarawa and (Alex) Coles who took dings and also young Tommy Lockett.
"We were a little bit thin in that area but we should be alright (for the game against Ospreys) this week."
One player who was available last Friday was prop Danny Hobbs-Awoyemi.
The loosehead got 20 minutes under his belt as he made his first appearance for almost a year, having suffered an Achilles injury against Bristol Bears last September.
"It was a good blow out for him," Boyd said.
"We could have given him a few more minutes because we ended up with about five props in the forward pack there at the end.
"He's had a long road with his Achilles and he'll be pleased just to get the minutes under his belt."