49ers displeased with Super Bowl practice field, sources say

Field conditions for the San Francisco 49ers' practice facility at UNLV have been met with widespread disapproval from various members of their organization, sources told ESPN's Adam Schefter.

The NFL put in a sod field on top of field turf and started laying it just last week when the NFL ordinarily requires Super Bowl practice fields to meet certain standards in December, sources told Schefter.

The NFL hardness score for fields averages 78, with no field being less than 70. The 49ers field is considered in the 50s, sources told Schefter.

"We've had 23 experts out there. We had the union out there. All of them think it's a very playable surface," NFL commissioner Roger Goodell said at his Super Bowl news conference on Monday. "It's softer than what they practiced on, but that happens. It's well within all of our testing standards. It's something we think all of our experts, as well as neutral field inspectors, have all said unanimously that it's a playable field."

The Kansas City Chiefs are practicing this week at theLas Vegas Raiders' training facility.

The league inspects the playing surfaces along with the NFL Players Association before every Super Bowl and approved each facility for use this week.

The playing surface was a storyline in Glendale, Arizona, for the Super Bowl last year, specifically the slick track that led to the Chiefs and Philadelphia Eagles struggling to find sure footing throughout the game.

CBS Sports first reported the 49ers' displeasure with their practice field.

Field Level Media contributed to this report.