Of these bowlers how many avg; <25 ? Only Murali,Steyn & Philander. Isn't it? Ashwin has yet to play a lot in difficult countries & i am sure his avg: will difenitely go a lot outside 25 in the end. Kapil faced bowlers not only with <25 avg: , there were several of these in low 20:s like
Ambrose,Hadlee, Marshall,Garner,Schultz too. What not Kapil faced likes of Morrison,Chatfield,Mushtaq Ahmed,Iqbal qasim, Sarfaraz Nawaz,Qadir, Patterson, Dilley,Fraser,Mcdermott,merv Hughes,alderman, Lawson, Dymock,Craig Mathews etc etc too who are a second tier group & comparable to the names you mentioned. Now a bowl avg: of 25 is equivalent to 50 bat avg: . That means if a bowler avg:s 24 , he is equivalent of a batsmen who avg:s 52( for a batsman his difference in avg: need to increase by twice when compared to that of a bowler).
You base this factor when analysing the quality of bowlers Kapil faced & then his bat avg: .