I imagine it's a good "in" to learn about their social life, which can lead to secrets being divulged. If you know where and how often they play sports, it's probably not terribly hard to arrange for your colleague to bump into them at the golf course (or wherever) and try to strike up a friendship. It's not as if the spy agencies had cellphone GPS logs to track these guys, so the human element was important.
Even asking a regular customer, "Hey, what happened to Ivan? I haven't seen him around. Is he still in the area?" while they're shopping for sports equipment could be a conversation that provides valuable information about someone's whereabouts.
Even asking a regular customer, "Hey, what happened to Ivan? I haven't seen him around. Is he still in the area?" while they're shopping for sports equipment could be a conversation that provides valuable information about someone's whereabouts.