Would hate substitutes in any form to be brought in.
Bowling @ death is an advanced form of defensive bowling. If you dont have yorker MAINLY, along with clever variations such a the slower deliveries, slower bumper - you will get smashed.
Alot of great bowlers in tests didn't have these pre-requistes thus would struggle in this format.
Any cricket match where a bowler is going @ 6 rpo constitute a fair balance between bat & ball.
In a T20 game given the way batsman go crazy in the first 6 overs. The threat of swing 9/10 times is irrelevant.
Look at Anil Kumble, throughout 2008 in test macthes he clearly had lost his zip. But he went straight into the IPL as was superb why?. Because he still had solid variation & guile.
Haa...thats the entire problem right here. Since when is cricket can 7-8.5 rpo be considered acceptable??? my word..
For the quicks if you couldn't bowl @ the death in a 50 over game you will be a poor T20 bowler.
For the spinners if you dont have guile & depend on darting the ball around i.e England's Snape & Schofield 07 WC, you will turn into a satellite.