When the Chicago Bears hired former Cincinnati Bengals offensive coordinator Bill Lazor earlier this off-season, they solidified a connection between the two franchises.
Insider Benjamin Allbright suggested that despite claiming Mitchell Tribisky was their quarterback for next season, Bears ownership is looking at bringing in competition for the former second overall pick. Their preferences just so happen to perfectly fit the parameters of what Andy Dalton brings.
Combine that with the previously mentioned fact that Bill Lazor is now heading the offensive operation in Chicago, and the reasoning for the two sides to come to the table for trade talk makes sense.