Looks like the 1800 team charter flights no longer show up on the UA flight status or even flight aware. Can't see any MLB charters for the start of this season. I know if is possible for the airline to request this information not made public. I was trying to find status of UA is 1801 PHX-IAH for today and see no charter at all on this route. I always enjoyed tracking this flights.
Flight Aware even has a disscussion board for this.