Tinsley has been a regular for Napier this season, scoring seven goals, but Robertson feels he can get a lot more out of the raw Englishman.
"I spoke to Ryan before the game and said that he really had to take some ownership now. And he's had a great game, scoring that hattrick. He's really taken ownership and was probably the man of the match today.
"He has a lot of ability but he's only a young lad. He's 20 now. And often people expect the older players to control the game more so I am challenging him to do it more because he does have the technical ability and, hopefully, we can develop him and push him on a bit."
Tinsley's hattrick takes him to 10 goals for the season, one behind teammate and teen striker Angus Kilkolly.
Saturday's match was played in the conditions that Wellington can often throw up, raining virtually the entire game.
Robertson made several changes with Josh Stevenson, Stu Wilson, Matt Hastings, Danny Wilson, Chris Greatholder and himself all out of action, meaning game time for fringe players Oli Chapman and Josh Anstis.
Nevertheless, the Blues, looking for a second win at Redwood Park after their 4-2 Chatham Cup win two weeks ago, started briskly to dominate the first half. Daniel Ball's back header was scooped away by the Tawa stopper but only to the feet of Sam Messam who side-stepped a defender before shooting from close range for the opening goal after nine minutes.
Miles John and Tinsley came close to increasing Napier's lead before the former Nottingham Forest and Leicester City apprentice squeezed the ball under the goalkeeper from a great Anstis pass before the interval.
On the hour mark, Tinsley brilliantly swept the ball in the far corner from distance out for Napier's third. Hopes of a clean sheet were scuppered when Tawa's Russell Kyne opened up the Napier defence for Todd Painter to score.
Like their Chatham Cup victory, Tawa remained a threat but, despite driving rain, the visitors kept up the pressure. That paid off when Andrija Ilic's free-kick was parried but only to John who was bundled over trying to get to the rebound. Tinsley's hattrick goal came form the penalty spot.
Ilic waltzed through the Tawa defence and calmly scored Napier's fifth with six minutes to go.
It was an impressive victory and one that keeps some pressure on the runaway leaders Miramar Rangers.
"We need to continue our good form, chase Miramar and keep this run going into the Chatham Cup quarterfinal match [against Island Bay Utd]," said Robertson.
Miramar Rangers continued their winning streak but only just, scraping past Lower Hutt City 1-0.
In other matches, Wellington Olympic eased past Upper Hutt City 7-2 at Wakefield Park, Western Suburbs beat Wairarapa 3-0 away and Petone beat Palmerston North Marist 3-1 on the road.
Miramar (11 games) have 33 points on the league table, Rovers (12 games) are on eight as are Olympic (13 games), with Western Suburbs on 20.
