Plazbot,
Leaving the star that late only gives you 6 minutes in the cruise to adjust your speed, which will comfortably only give you about +/- 30 seconds. This then leads to descent speeds and profiles which are wildly different from the standard un-impeded profile that would normally be flown, so ATC won't be able to predict what each aircraft is going to do to try to satisfy the fix crossing time. After finally satisfying that requirement at V-min+companyrequirement and the speed brake out, once past the fix speed restrictions are quite often lifted and track shortening is given to help the flow past the fix.