In this article, Chistopher Martin Jenkins pays tribute to Gilly and names other cricketers who have changed the way the game of cricket is played.
Jardine (rutheless pursuit of victory)
Lloyd (no need for spinners)
Kapil (shifting the power base from London to India)
Jayasuriya (role of openers in one-dayers)
- are his choices, apart from Gilly for changing the role of wk-batsman.
I think the impact he is attributing to Kapil is a by product of the result he achieved rather than a clearly measurable contribution. Also Jardine's captaincy turned out to be a one off thing and, till date, has not become the blue print for English captains.
My choices would also include:
leg glance - until then one sixth of the cricket ground was under used by the batting team. it changed field setting theories irrevocably
reverse swing - only after this innovation could fast bowlers play an effective role with the old ball in otherwise spinners only situations