The Tigers are bracing for the loss of forward Alex Seyfarth for an extended period after he was forced from the ground with a knee injury following a tackle that landed Manly's Josh Aloiai on report.
Seyfarth was in a brace after the 44-24 loss to the Sea Eagles at Suncorp Stadium, with Tigers staff confirming an MCL injury to his knee and Maguire saying "it's not good" for the 22-year-old.
Aloiai was the third man into a tackle on Seyfarth in the 31st minute and cannoned into the Tiger's legs, sending him slumping to the turf.
Already down a man after second-rower Luke Garner was forced off with an ankle injury after 15 minutes, the Tigers were unable to activate their 18th man with Aloiai not sin binned or sent off.
"It would have been nice to use the 18th man there, it goes on report but if he doesn't come off, we can't use that 18th man, so it is what it is," Maguire said.
"But we did lose a few troops there.
Match Highlights: Sea Eagles v Wests Tigers
"Alex and Luke came off in the first half, so I commend the boys for working extremely hard in those circumstances but we had ourselves in a position to compete and we should be better at handling those sorts of things."
The 18th man activation can only occur currently if a team loses a player to concussion after an act of foul play where the player responsible comes off the ground, or if three players are lost to HIAs during a match.
"I want to review the tackle before I make a judgement on (whether there should be a case for the 18th man to be activated) that but we lose a player in that circumstance and you've got the 18th man there," Maguire said.
"We can use the 18th man around the concussion rule but in this case we'll have to have a look at it, because he's got to get 10 minutes in the bin to ignite the 18th man."
Maguire was not blaming the loss on the absence of his forwards, admitting his side had plenty of opportunities in the first half.
After regaining Daly Cherry-Evans and Tom Trbojevic from Origin duties, the Sea Eagles were heavy favourites but the Tigers punched above their weight early to go 12-10 up in the shadows of half-time after Adam Doueihi scored and converted.
Sideline to sideline go the Wests Tigers as Maumalo grabs a double
"We had them under pressure there, we had back-to-back sets and then we had a scrum and dropped a ball at the back end and in the last five minutes of that half they scored two tries," Maguire said.
"We felt at half-time we were putting ourselves in the game but lapses in the game hurt us."
"We had good completions, we had good possession of the ball but it's our execution at moments in time with our attack when the opportunities come about.
"We'll look at that and get our spine working hard in those positions as well."
