Don't know what makes sportsmen and even some management gurus think that "Being Ruthless" in achieving your goals is the best option to succeed. In the cricketing context, was our earlier teams were not ruthless and allowed opponent batsmen to score some 5o extra runs or bowlers to take 2-3 extra wickets out of 'mercy' or 'compassion'? Or did they trade for return benefits? Yes, may be we can say you must be ruthless towards your self-doubts and give 100% on the field. Even then to say 'be ruthless' is a rudderless advice...
