Because Ed Wade's list of managerial candidates apparently runs more than two pages.
And in the first paragraph of the story, Cardinals pitching coach Dave Duncan denied any interest - at least until the season ends. Duncan:
“My interest right now is to be the best pitching coach for the St. Louis Cardinals for the remainder of the season and through the postseason. I don’t really want to get distracted with anything that’s going to take away from that. I’m just going to concentrate on doing my job right now and finishing the season...
...Earlier in my career, I think I had a desire to manage more than I do now. I don’t think that you go into the job like that without making a really strong commitment. And usually it has to have some length to it. So my interest right now — you know, I’ve been around a long time, and I don’t know whether I’d have the same desire to make that type of commitment than I might have in years past.”
With a two-page-plus list, I would imagine that every bench, 3rd base, and pitching coach is on Wade's Pro/Con list.