This is a mix of “keep an ear to the ground” (alert and listening for clues) and “keep your eyes wide open (or peeled)” (vigilant and watchful). This subtle conflation was heard on Bloomberg news:
Question from interviewer: how do you have such success picking funds?
Ans: we keep our eyes to the ground.
The speaker quickly corrected himself and said: “We keep our ears to the ground and look ahead.” Self caught malaphor. Nice. A big thank you to John Costello for hearing this one.