The four-year-old had won four times last season but was still trailing the colts and geldings on ratings as her mark of 86 left her 18lb behind her nearest-ranked rival.
That divide in estimation did not replicate itself on the track, where Astral Beau made light work of the heavy ground to come home four lengths ahead of Michael Dods' Brunch with the rest well spaced out behind her.
A step up to Group Two level is now under consideration for the daughter of Brazen Beau, with Sly pencilling her in for the Dahlia Stakes over a mile and a furlong at the Newmarket Guineas meeting.
The trainer said: "I'm thinking of the Dahlia at Newmarket on May 7, we might have a go at that over nine furlongs because I think she'll stay.
"She didn't pull up until she got to Rose Hill the other day! It will be interesting to see what handicap mark she gets.
"When she gets to the last 100 yards, she starts to go away from them then. She's done that in her other races, she gets there and you don't know if she's going to win and then all of a sudden she's gone away again. It's a lot of fun."
Soft ground will be essential to the filly's participation throughout the season, with Sly striking early in the term and expecting to let her homebred sit out the summer months when the going is at its quickest.
"She does need a bit of give in the ground, everything revolves around that I think," she said.
"I knew she was behind the boys, but it will be interesting to see where she goes as long as it keeps raining!
"That's why I've had them ready early, all of mine like the dig in the ground so I had her ready to go early and she'll have to go on a holiday in the summer."
The filly is from the family of Sly's 1000 Guineas winner Speciosa, who triumphed in the Classic in 2006 and then produced a Sea The Stars mare called Asteroidea – the dam of Astral Beau.
The bloodline is one Sly continues to cultivate as Eileendover, a Listed bumper winner by Canford Cliffs, is also a granddaughter of Speciosa as she is out of the mare Specialty – dam of three runners who have all won races.
Of Astral Beau, Sly said: "She's from the Speciosa line, from Speciosa's second daughter – the Sea The Stars mare Asteroidea. The first daughter, the Oasis Dream one (Specialty), she's bred a Listed winner as well in Eileendover and now the second daughter has also bred a Listed winner.
"We've got a Teofilo mare as well, Vernatti, she hasn't had a runner yet but she's got one to go this time, a three-year-old.
"If you're a bit nerdy, it's very much a fillies' family. If you look back through Speciosa, there's (three-time Group One winner) Pride through that line, there's just a load of good fillies."
The family also produced ex-James Ferguson runner Mise En Scene, sixth in the Breeders' Cup Filly & Mare Turf and out of Specifically, a sister to Speciosa.
Sly said: "There was a filly who ran in America in November time who finished sixth and she was out of Gadfly, who is a sister to Speciosa.
"It's very much a fillies' family and I find that quite interesting."
