Do you realize how complex it is to install a grass surface. Its more than just laying down sod. There is only 3 months out of the year where Seattle can actually work on putting a grass service and that's between the NFL and MLS season. I believe Seattle said they would have to shut down CenturyLink field for 8 months in order to install a grass surface as well as everything else necessary to have a grass service. Ie a proper drainage system. They aren't gonna shut down the stadium or move a team (seahawks or sounders) to temporary facility somewhere else.