The result means Wolves can be assured of automatic promotion, and almost certainly the title, this weekend by beating QPR at Molineux.
Asked whether Blues were battling for second now, McLeish said: "I think realistically yes.
"But we'll keep going, we've got to go to Watford and win and try and win the rest of our games.
"But if the league finished today, with us second, then I think we'll be quite happy."
The point gained against Plymouth will go down as one gained in the circumstances, but would have been looked upon as two dropped before kick-off.
The game's main talking point occurred in the 23rd minute when Maik Taylor was given his marching orders for bringing down Jamie Mackie, who was bearing down on goal with Liam Ridgewell chasing behind.
Referee Michael Oliver adjudged the foul to have happened inside the area, although replays later proved the Plymouth striker was upended outside the box. And McLeish later revealed Blues will file for wrongful dismissal.
Paul Gallagher tucked away the resulting penalty, leaving 10-man Blues chasing the game. But Franck Queudrue's header rescued what could prove to be a crucial point for the hosts.
But Birmingham's afternoon was also soured by the news defender Ridgewell innocuously suffered a suspected broken leg in the first half, with his season now likely to be over.
"I'm proud of the players, I'm really proud of them," said McLeish.
"Their efforts, their spirit, their heart, the fire in their belly, they were absolutely knackered.
"I think the game against Wolves with 10 men took its toll at the weekend (against Charlton), today we found another spark. I think we got at least what we deserved, I'm disappointed with the time we had left when Franck scored that we didn't go on and win it."
Regarding the penalty, he added: "It's not even in the box first and foremost, Maik also thinks he kicked it off the lad."
Argyle manager Paul Sturrock admitted his side had been fortunate with the penalty decision but couldn't help feeling disappointed not to have secured all three points in their battle to avoid the drop.
"I've been told it wasn't a penalty but there's been three of four times this season we've had penalties that we haven't got, so we'll take the lady luck that shone on us today," he said.
"Their goalkeeper was also very unfortunate (to get sent off), but I thought the referee handled the game very, very well.
"Their keeper has made a couple of decent saves and we've had a couple of goals disallowed for offside. I've got a disappointed squad in there.
"It's not often you come to a place like this and feel disappointed you didn't take the three points.
"We're starting to shape a team together."