So far this season, Richie Sexson has 10 measly hits in 69 at-bats. But of those hits, six are doubles and three are home runs, leaving only one single to his credit. One might wonder whether Sexson can continue to get 90% of his hits for extra bases (and then one should quickly answer "no"). But I looked back the past few years to see some of the largest XBH percentages (it's times like this where you wish you had Elias databases and search tools at your disposal).
So far, the only players with the requisite number of at-bats that even reach the 60% threshold are Travis Buck (67%), Torii Hunter (64%), Alex Rodriguez (64%), Chase Utley (62%), Khalil Greene (62%), Curtis Granderson (62%), and Andruw Jones (62%). 18 others at least meet the 50% threshold. But there can be quite a variance when the sample size in at-bats is so small, so I looked at the data for the past few years.
In 2006, the only qualified players to cross even the 50% plateau were Carlos Beltran (57%), Jason Giambi (55%), Bill Hall (54%), David Ortiz (53%), Travis Hafner (53%), Adam LaRoche (51%), and Carlos Delgado (50%). In 2005, the only players to do so were Adam Dunn (57%), Jim Edmonds (54%), Sexson (52%), Hafner (51%), Andruw Jones (51%), and Jason Lane (50%). In 2004, the players reaching 50% were Barry Bonds (56%, in his ridiculous .362/.609/.812 season), Edmonds (55%), Mike Cameron (54%), Dunn (53%), Ortiz (52%), Beltran (52%), Jim Thome (51%), Vinny Castilla (51%, pre-humidor), Brad Wilkerson (50%), and Carlos Pena (50%).
So what's common among these groups of players? First, they all are players who hit for power, because you can't rack up extra-base hits in the majors without at least gap power. Second, these aren't, for the most part, players who regularly hit for average, other than Bonds' unconscious 2004, Hafner, and maybe Beltran and Ortiz to a certain extent. Which again makes sense, because players picking up a lot of hits will invariably rack up singles, reducing their percentage (note the conspicuous absence of Albert Pujols from this list, and A-Rod prior to this season). Third, it seems like a few players on this list at least have a modicum of speed (e.g. Hall, Beltran, Cameron, and note the absence of Frank "blazer out of the box" Thomas), which again makes sense, as these players turn percentage-dragging singles into doubles.
Obviously, Sexson's 90% rate is going to come down. But after doing this research, I tried to look up a few guys who might fit the criteria, but couldn't find anyone significantly over the 50% mark. So can anyone think of players in the past who (1) hit for power, (2) didn't hit for a high average, and (3) had above average speed, who might have topped the 60% mark (or dare I ask the 70% mark) in a season? Make sure that they've received enough at-bats to qualify.