Castleford, whose season consisted of a long and ultimately successful battle against relegation, go to Bradford tomorrow to meet the runaway winners of Super League.
"Under this system, it's a level playing field and it comes down to 80 minutes of football," Raper said. "I'm thankful for that, but it's ludicrous that Bradford could be knocked out by us and the team that finished two from bottom could go on to win it."
Raper would favour the system used in his native Australia where the teams finishing first and second get two chances to progress. This year, however, Cas will try to exploit the rules as they stand. "I'm very pleased at the way we've turned things around," he said. "It has been partly a matter of making some crucial signings, like Jason Critchley, Richard McKell and Brad Davis, but also of the players who were already here improving their form." Raper is waiting for fitness checks on Dean Sampson and David Chapman before finalising his side.
The Rugby League has suggested a solution of almost biblical simplicity to the problem of both New Zealand and Bradford possibly needing Robbie Paul on the same weekend.
If Bradford are involved in the Premiership final, they have suggested to the Kiwi coach, Frank Endacott, that he takes his brother, Henry, instead.
If the quarter-finals go to form, with Bradford beating Castleford and Wigan accounting for Leeds on Monday, the two clubs will meet in the semi- final. The League's suggestion is that New Zealand should then take the Paul who is on the losing side for the Test against Australia on 26 September.
Cronulla's Tawera Nikau has withdrawn from the Kiwi side rather than play alongside his one-time Castleford team-mate, Richie Blackmore, who is now with Leeds.
The League has also complained about the timetable for the World Club Championship quarter-finals that involves Bradford flying to Auckland on 1 October and playing two days later.
In tomorrow's other Premiership quarter-final, Peter Gill returns for the London Broncos, at home to Sheffield. Terry Matterson moves to hooker and Robbie Beazley to stand-off, in the absence of the injured Tulsen Tollett.
Apart from its significance to a London club that has set its sights on the Old Trafford final, the tie represents a chance for the Great Britain veterans, Shaun Edwards and Martin Offiah, to show that they should be called up for the Tests against Australia in November.
The opening Test, at Wembley on 1 November, is to be the first to use the video referee and giant screen replays.