The Grammys exists to honor all genres of music, and therefore organizers gathered some of the youngest, hottest names in country music to perform together at the awards ceremony on January 26: Merle Haggard, Kris Kristofferson, Willie Nelson, and the relatively senior Blake Shelton.
We jest of course. The first three listed might not be the youngest or hottest names in country at the moment, but they command a huge share of renown and influence in the genre's history, both as performers and songwriters. Shelton might not have merited the esteem of his cohorts yet, but as one of the most recognizable names on modern country radio, could be on his way.
So what DO the four have in common? They all hail from Oklahoma and Texas. Or at least that's what the Grammys claims. Haggard is actually from California, but his parents migrated from Oklahoma during the Great Depression, and both Nelson and Shelton are Okies. Kristofferson was born in Texas. The significance is all for a good cause, so we shouldn't critique: The performance will be to raise awareness for continuing relief efforts in the two states following the May tornadoes that hit the area.
Kristofferson and Shelton will be at the performance anyway, so they might as well get onstage and perform. The former will be receiving the Grammy Lifetime Achievement Award the night before at a special ceremony, and the latter is nominated for two Grammys: Best Country Solo Performance ("Mine Would Be You") and Best Country Album (Based On A True Story). Even if they aren't receiving awards, no one complains about Haggard and Nelson being present at country performances.
It will be Haggard's first performance at the Grammys.