batsman replacing batsman OR bowler replacing bowler is not good as well.because say Hogg is not in my team but Tait is and Hogg scores a 70 runs by 10:30AM, now i will smartly say Hogg is bowler as well, so i replace tait with hogg!same applies for Sachin, Yuvraj, Ganguly, Symonds. so its better to give freedom to choose bowler for batsman as long as weightage is similar. say difference of max 30.also game is super selector which means to prove that u r the best selector. now if the team u predict b4 match is very different (weight distribution) from team u declare with substitution, it shows that even if ur score is high u were not able to select correct team b4 hand.other suggestion of score < 30 for player substituing is to prevent ppl increasing their own score too much (by already knowing that player has already performed well)