Just my impressions of these boring guys . . .
Federer . . . a little bit tortured when he plays. Flamboyant tennis aside, there's this obsessive, searching element in a lot of his games where I'm not sure whether he's trying to figure out his opponent, figure out his stroke, or his nerves. When he wins, it's almost like a relief from the concentration. And it almost feels like he's violating other people's games. When he talks about his game, I think in a way, he wants to relate to the press this process rather than the technical elements.
Sampras . . . he wants to be respected and stubbornly stuck to the dictum "my actions speak for themselves" onto the public imagination. His style of play is stubborn, macho, but also beautiful and elegant. He was almost idealogical about his game, believing in its purity, and then imposing that purity onto the tennis world. I've never found him boring, just offputting. You tend to either greatly admire/love his game or feel it's a little oppressive (even obnoxious), because it gave no quarter to almost no other player.
Borg . . . best thing about the Royal Tennebaums.
Wilander . . . I guess I kinda see him as the Greg Maddux of tennis. And for some reason, I get the vibe that the thing he liked most about the pro career wasn't the titles, but getting sloshed with the other guys after hours.
Lendl . . . Dude, Lendl was like the Evil Empire of the Reagan 80s; you had to hate him because, well, he was so "un-American." I didn't think he was an actual, breathing human being until close to his retirement. But he may be the most interesting guy on this list because he seems to just relish irony of playing some kind of vague villain to us yankee yahoos. Everything was just show.