Agreed, and I've always lamented England's policy of often selecting inferior bowlers because they can bat a bit (e.g. when the out of form Ashley Giles was preferred to the in-form Monty Panesar under Fletcher for this reason) but if you're in at 9 you need to be closer to 15-20, and be able to hold an end up. Archer is looking more like a 10-11, yet we have someone with a Test ton (admittedly his batting has gone downhill since he got a knock on the bonce) at 11.His job is to take wickets, not score runs. Bowlers are lucky to average 10 in test matches.
Leach, who I believe is averaging 4 in domestic Cricket this season, seems well suited to this role. Dig in, let the batsman at the other end do the bulk of the scoring.