How useful it is to have an opening batsmen who we can get ten reliable overs out of on a regular basis?

Mohammad Hafeez this year has bowled 9 or 10 overs in a one dayer 11 times and the highest the off spinner has gone for is just 43 in his full allocation:

1-26 (10) vs. Australia on 19/03/11

2-16 (10) vs. West Indies on 23/03/11

1-34 (10) vs. India on 30/03/11

1-36 (10) vs. West Indies on 23/04/11

2-38 (10) vs. West Indies on 25/04/11

2-31 (9) vs. West Indies on 28/4/11

1-42 (10) vs. Ireland on 30/05/11

1-38 (10) vs. Zimbabwe on 08/09/11

0-43 (10) vs. Zimbabwe on 11/09/11

1-37 (9) vs. Zimbabwe on 14/09/11

2-24 (10) vs. Sri Lanka on 11/11/11