"They're critical (wins) for us at the moment," said McFadden.
"We've been in some tight battles over the previous weeks before the Newcastle game and we fell at the last hurdle, so to get one is an important step."
Listen: Audio highlights of the Warriors' round five golden point thriller
The Warriors started badly and trailed 8-0 after 11 minutes following a converted Kenny-Dowall try and a penalty goal to Jackson Hastings.
Tries to Manu Vatuvei and Solomone Kata got them into the match, and two more in two minutes to five-eighth Shaun Johnson put them in from before Kenny-Dowall crossed for his second, but they held the lead at the break - for the first time this year - 20-14.
In a high-scoring but error-strewn affair, they fell behind by six when the Roosters scored two quick tries early in the second-half through Sio Siua Taukeiaho and Mitchell Aubusson.
But the Warriors kept their composure and took the next chance on offer, with Kata scoring his second and Johnson converting to level scores in the 58th minute.
Warriors' impact player Konrad Hurrell arrived off the bench but lost possession on a yardage carry and then gave away a penalty as the both sides struggled for momentum.
The Roosters were enjoying more sustained attack but with over a quarter of the match remaining they hesitated, easing the pressure on the visitors by opting for goal with Hastings kicking his second penalty for a two-point lead.
After being criticised last week for his form, fitness and poor media relations, Issac Luke was at his probing best out of dummyhalf and posed numerous problems for the defence.
With his spark around the ruck, the Warriors came close to laying on a try but calmly settled for a Johnson penalty to draw level at 28-28 with six minutes left.
Heeding lessons from their heart-breaking round three defeat to Melbourne, Johnson promptly set up for a field goal but an ordinary pass from Albert Vete saw a wobbly low attempt go under the crossbar.
The Roosters then took their turn at the one-pointer, but fullback Lattrell Mitchell's kick sprayed wide, before two further shots from Johnson were charged down and then skewed away as the full-time hooter rang.
The Warriors defended well off the restart and maintained their attacking mind-set when Lolohea climbed to collect a high ball under pressure from two Roosters' chasers and beat four more defenders on a jinking run, before Tuivasa-Sheck scorched away to secure two competition points.
"It was a pretty good moment for him, but he'll be feeling for his ex-teammates," said McFadden.
"It was a bit of a challenge for him this game. He played a bit of time with that club so it was a good moment. He played well."
Warriors 32 (Manu Vatuvei, Solomone Kata 2, Shaun Johnson 2, Roger Tuivasa-Sheck tries, 3 cons, 1 pen)
Roosters 28 (Shaun Kenny-Dowall 2, Sio Siua Taukeiaho, Mitchell Aubusson tries, Jackson Hastings 4 cons, 2 pens)
