Whatever, all said and done, Hadlee was a better bat than Marshall and he would be replacing McGrath a bunny.
Just saying McGrath is better because of peer rating doesn't mean he wasn't incredibly close to McGrath as a bowler. You still seem unable to talk about skillsets.
Skill set and compatibility.
McGrath had an unmatched ability to target wickets with the new ball at the top of the innings. He also had the knack to dismiss the best batsmen from opposing teams.
His value per wicket is up there with the likes of Marshall, Ambrose and Davidson and his percentage of top order wickets taken is representative of that. He is very arguably the best new ball bowler in history.
He was able to sustain his success in the flat pitch era though his unmatched accuracy, subtle seam movement and ability to extract bounce from even benign wickets. He never stopped coming at batsmen, while Hadlee was known, like Ambrose to drop onto defensive mode when things weren't going to plan.
He played on flatter and less conducive wickets to Hadlee and had less access to the tail and to minnows, which Lillee maximized his output against.
With regards to this team in question, his bounce and seam stands in contract to Marshalls pace and swing, and his skiddy bounce vs McGrath's more steepling offerings.
Marshall and Garner were at their best when they also presented that combination to opposing batters and they tested differing aspects of the opposition's technique and will. McGrath was also more adept at bowling into the wind.
He had greater competition for wickets and still maintained an elite wpm and most importantly he was the vehicle that elevated a great team into one if the two greatest of all time.
He has the numbers, the skill set, the peer rating, the intangibles, the compatibility and tougher conditions.