The following is the frequency analysis of the Sherlock puzzle:

4  BBBB
9  CCCCCCCCC
6  DDDDDD
4  FFFF
3  GGG
6  HHHHHH
1  J
2  KK
6  LLLLLL    
5  MMMMM
17 NNNNNNNNNNNNNNNNN
5  PPPPP
1  Q
12 RRRRRRRRRRRR
9  SSSSSSSSS
17 TTTTTTTTTTTTTTTTT
4  VVVV
6  WWWWWW
1  X
3  YYY