The article says "The 27-year-old Jalandhar native is India's most successful off-spinner, having taken 238 wickets in 57 Tests and 174 wickets in 151 one-day games."
In the famed days of the legendary spin quartet, three spinners used to be fixtures in the team with Venkat and Prasanna fighting out for the fourth slot (more often poor Venkat). Pras and Chandra (as they were lovingly called by fans those days) used to bamboozle the top order of the world's top flight batsmen from England, Australia and West Indies, while Bedi gleefully picked up tailenders!
In the late 70's through early 90's, importance of spinners was downplayed with the arrival of a pack of promising and good pacers led by the legendary Kapil Dev and so we had run of the mill spinners like Dilip Doshi, Shivlal Yadav, Arshad Ayub, Ravi Shastri, V Raju, Maninder Singh etc.
Then came the colassus called Kumble (Jumbo) who to date is the real most successful bowler of India. I don't want to explain. Go to cricinfo.com and analyse the number of wickets taken divided by number of tests played by any leading bowler - Kapil, Kumble, Bedi, Srinath, Chandra ... you will agree.
Well, wait, I am only saying that Kumble is the only real SUCCESSFUL bowler. I am not saying that he is the best.
In my own assessment, Harbhajan is the best spinner ever to have played for India. Reasons: Aggression, Killer instinct, will to succeed. Bonus: Better fielder than any other Indian spinner (barring Venkat)