First, the basics. Craig is the new receivers coach in Baton Rouge after holding both that title and co-OC on the Plains from 2013-15. Before that, he was quarterbacks coach at FSU from 2010-12 when he worked with future first rounders E.J. Manuel, Christian Ponder, and Jameis Winston. At both of those stops, he was the program's recruiting coordinator.
Two sources close to the situation said Craig is leaving because of concerns about how the offense was being run and how he fit. Those concerns grew to a point that Craig believed he no longer fit the program and that it was was time for him to leave.
Though Craig has shown good chops in player development, it's the recruiting that he's most known for. LSU's release highlights that he was both the Scout.com recruiter of the year and Rivals.com ACC recruiter of the year for 2012 when he landed Winston. In the 247Sports recruiter rankings, Craig placed fourth in 2016, eighth in 2014, and third in 2012.
When it has a coach who isn't asleep at the wheel, LSU does a great job of keeping in-state talent at home. Les Miles has consistently done that, although he has lost some good players to Alabama in recent years. Craig's area of specialty in recruiting is southern Alabama and Florida, so he might be able to snag some players to compensate for Nick Saban's encroachments.
It's hard to say what this means for Auburn. Craig has been vocal about wanting to climb the coaching ladder, and it would seem that he decided that he's got a better chance to do that at LSU. Though he was co-OC at Auburn, there isn't really any sign that he got to do much actual OC work with former Gus Malzahn quarterback Rhett Lashlee being the other half of the "co" arrangement.
Perhaps Craig thinks that he can wait in the wings for a year or two for Cam Cameron to retire and ascend to a real OC job at LSU. Perhaps he thinks that working under Cameron will prove more beneficial to his professional development than doing more years under Malzahn would. After all, going back to a more pro-oriented style at LSU like he coached at FSU probably does more to make the NFL a viable option than working for Malzahn does.
Either way, Auburn lost its top recruiter to a division rival. With Malzahn's regime struggling to recreate the 2013 magic, this is not going to help. Meanwhile, LSU gained a top talent magnet who is highly motivated to do a great job. It's hard not to think this will make the Bayou Bengals better in the near future.