UPDATE: According to Ian Rapoport of NFL Network, the Steelers final offer was a 5 year worth $70M, averaging $14M per season, and with more than $30M in the first two years deal. The offer included $33M in guarantees. Rapaport also stated that over the first 3 years of the deal, it would average $15M per year, and obviously that would equal $45M in 3 years.
The Steelers and Bell were a lot closer than originally reported. The Steelers and Bell will try to negotiate one more time after the 2018 season concludes.