___________UPDATE____________
As good a place as any to note a Robby Mook = Mother Jones feature (not to be confused with Mookie Blaylock, whose skills are in a different arena).
There is a lot there, like this, which gives a flavor:
Clinton Inc. Planet Hillary. Hillaryland.
Whatever it's called, this is the vast network of advisers, fixers, donors, lackeys, celebrity pals, old campaign hands, State Department staff, friends of Bill, friends of Hillary, and friends of Chelsea that surrounds the Clintons. "They just keep building on all of the people who are well intentioned, well meaning, extremely loyal, but all have an opinion and want to be heard," says Patti Solis Doyle, a former aide and friend of Hillary dating back decades.
[... Mook] couldn't be more different from, say, James Carville, the loudmouth Ragin' Cajun who advised Bill Clinton's first presidential bid and now makes a living as a consultant and TV commentator. Mook rarely appears in news stories or on TV. He did not respond to repeated interview requests. He has no Facebook page. He has a Twitter account but never tweets and has forgotten the password.
[...] Think of Mook, then, as the Hillaryland Whisperer. But Mook can't focus on Clintonworld alone. He will also need to manage the influx of Obama alums expected to join Hillary's team and ensure that old grudges and bad habits from the 2008 campaign don't resurface. (John Podesta, Bill Clinton's chief of staff who went on to lead Obama's transition team and now chairs Hillary's presumptive campaign, might be able to help with that.)
Mook can't eliminate all of the internal chaos that sunk Solis Doyle. He can't reshuffle Hillary Clinton's inner circle to his liking. His charge will be handling the egos, absorbing the sharp elbows, and putting to good use the brains, money, and connections of the ever-expanding Clinton universe.
"Hillary's not going to dispense with Maggie Williams. She's not going to dispense with Cheryl Mills. She's not going to dispense with Huma Abedin just because the new boy's on the block," says one Democrat close to the Clintons, listing three of Hillary's closest longtime advisers. "The new boy on the block has to learn who those people are, how to accommodate them, and, importantly, how to harness them towards the common enterprise. They all want Hillary elected, but they also all have their own turf."
[...] After graduating from Columbia in 2002 with a degree in classics, Mook spent a year as the Vermont Democratic Party's field director. Soon after the 2002 election, the state party's former executive director, Tom Hughes, recruited Mook to join the New Hampshire staff for Howard Dean's insurgent presidential run.
Not Karl Rove. Read the item to get a picture beyond that. He ostensibly heads the Clinton campaign. Whatever in the world that means.