By Wally Pyrah IN-FORM trainer Ricky Yui has been waxing lyrical over the past week about the chances of his Hong Kong Derby candidate, SIMPLY MAVERICK, who puts his reputation on the line in the TVB Miss Hong Kong Pageant Handicap (9.15am) over nine furlongs. This progressive son of Sebring has won three of his last four races and was only just denied when suffering interference in his defeat back in December. All of those victories have come over the extended mile at Happy Valley, but his trainer is adamant that there is plenty more improvement to come, especially with the long Sha Tin strai…