Multiple people who were hanging out with Tyler Skaggs on the day before he died tell TMZ Sports there were no obvious signs anything was wrong -- "He seemed completely normal."
One source tells us, "I was with him on Sunday. He seemed like himself."
Another source added, "There was no indication anything was wrong" ... saying the 27-year-old's death was "shocking," especially since Tyler had pitched just 2 days before he died.
Skaggs and the rest of the L.A. Angels flew from Anaheim to Dallas on Sunday ... and Skaggs was in such a good mood, he suggested the team take a funny Cowboy-themed team photo at the airport. He posted the photo Sunday evening saying, "Howdy ya'll."
The very next day, Skaggs was found unconscious in his hotel room -- and was pronounced dead at the scene when paramedics arrived.
Officials say there were no obvious signs of suicide or foul play -- and the medical examiner is currently investigating. An autopsy and toxicology tests have been performed but the results have not been made public. It could take between 4 and 6 weeks for the toxicology results to come back.
The Angels organization has said they have no information on the cause of death.