He has expressed satisfaction with the 26-6 result against the enthusiastic but limited Titans, but called his side "a little immature" for failing to kill them off in the second half. It appears the growing pains are not over just yet.
The coach will, however, have taken encouragement from the entirely more assured displays from a first-choice centre combination that has been under the gun this season.
Ben Henry's rock-solid 20-tackle, zero-miss performance continued his steady progression in the top grade, while Jerome Ropati bounced back from last week's tough outing against the Bulldogs with a stellar display.
"I'm buggered," Ropati said after running for 136m and producing 20 tackles in the sapping conditions.
"But, yeah, I felt better than last week. It was the toughest match I've had in wet weather."
After turning an ankle in his comeback match from a major knee injury and then being exposed by Ben Barba last week, Ropati was the subject of intense criticism leading into the Titans match.
He was occasionally isolated on defence but responded admirably, pulling off seven one-on-one tackles to shut down Titans raids.
"I've been in this game for 10 years and I have figured out a way where you can kind of focus on yourself and use the team and training and preparation to overcome all of that [criticism].
"I thought we played excellent footy in the conditions. We knew the Titans were going to throw the ball around and challenge our edges because of what we did last week," said Ropati.
"More importantly we are happy with the way we are sticking to our game plan and improving."
Halfback Shaun Johnson, who scored two of the side's five tries, indicated the team was still finding its feet under McClennan.
"If we can continue backing our structure, backing what Bluey tells us to do, it is going to go a long way towards winning games."
While Manu Vatuvei's early departure with a tight hamstring was precautionary, a question mark hangs over Kevin Locke after the fullback limped off with a knee injury.
Locke's understudy, Glen Fisiiahi, scored a hat-trick in the Vulcans' win over Manly in the curtain-raiser, taking his tally to nine in two matches.