For most of his glittering 17-year pro career Tony Gonzalez has been a marked man on fall Sundays. Don’t expect that to change in the Georgia Dome against the Tampa Bay Buccaneers. The 13-time Pro Bowl tight end might be Atlanta’s only proven threat in the passing game as the winless Bucs face the equally desperate Falcons (1-4). Leading receiver Julio Jones is already out for the season with a foot injury and Roddy White is out with a sore hamstring leaving Gonzalez as Matt Ryan’s most viable target Sunday. And like any leader Gonzalez has raised his game in times of stress catching 22 passes in the past two games after posting 11 receptions in the first three weeks. “He’s still a guy that they’re totally leaning on getting the ball in very key situations’’ Bucs defensive coordinator Bill Sheridan siad. “He is their guy and still perfectly capable of changing a game unless you do something to take care of him.’’ With the defending NFC South champions off to a 1-4 start before the bye week rumors spread that Gonzalez wouldn’t mind returning to the Chiefs (6-0) who selected Gonzalez in the first round of the 1997 draft.