When? We don't know. But it appears that the Snelling workout, if true, was part of the Kansas City Chiefs' due diligence as they were searching for a fullback type back. Snelling is that type of back, similar to Le'Ron McClain in the sense that they are both running back/fullback hybrids.
Snelling was drafted in the 7th round of the 2007 NFL draft and was barely used by the Falcons until Michael Turner was injured in 2009. Snelling had 142 carries that season and played pretty well. He has 105 carries in his other three NFL seasons. He is not really a full time running back.
Obviously the Chiefs were shopping around for this type of player. But don't expect Snelling in Kansas City now that FB Le'Ron McClain has reportedly agreed to terms with the Chiefs.
Snelling is essentially the last "quality" free agent running back on the market.
To learn a bit more, here are some of the latest comments on Snelling from The Falcoholic:
It's encouraging that the Falcons at least have the reasonable option to bring Snelling back, should they so desire. He's been a very solid running back over his tenure in Atlanta, catching passes, throwing blocks and yes, rushing reasonably well. Big Snell is, at the very least, a quality complement to Michael Turner and incoming Jacquizz Rodgers.
Let me be clear on this: If the Falcons can re-sign Snelling at a reasonable price, I'd be happy to have them do so. He's a great guy, a capable backup and someone who wants to be on the Falcons.