In the late 1970s, Roberts worked as an assistant pro at San Luis Obispo Golf and Country Club as well as Morro Bay Golf Course. He won the Foot-Joy PGA Assistant Professional Championship of 1979 and was second in 1980. The first professional tour where he briefly competed was the PGA Tour of Australasia, after his 1979 PGA victory. On his fifth attempt, Roberts earned his PGA Tour card at the PGA Tour Qualification Tournament in 1980 for the 1981 season. He returned to the tournament in 1981, 1982, 1986 and 1987, earning his card every year except 1981. He did not get his first win on the PGA Tour until 1994 at age 38, yet it sparked a nine-season run of eight victories. His career earnings are over $15 million. He is known as Boss of the Moss" for his putting skills. He has featured in the top 20 of the Official World Golf Rankings. Roberts' best finish in a major was when he tied for 2nd place at the 1994 U.S. Open. He contended in an 18-hole playoff with Ernie Els and Colin Montgomerie. Montgomerie was eliminated and then an additional pair of sudden-death holes gave Els the title. Roberts played for the United States in the 1995 Ryder Cup, 1994 and 2000 Presidents Cups, and 2001 UBS Warburg Cup. He was 3-1 at the Ryder Cup, 4-2-1 at the Presidents Cups, and 1-2 at the UBS Warburg Cup. Of the four team events, only the Ryder Cup team lost. He was a co-assistant captain for the 2006 Ryder Cup which was also defeated by the European team. After concentrating on the Champions Tour in 2006, Roberts went without a PGA Tour card for the 2007 and 2008 seasons, passing on using his exemption for being among the top 50 in career earnings. He used the exemption for the 2009 season. In 2005, Roberts joined the Champions Tour. His first senior win came in his third event at the JELD-WEN Tradition, one of five senior majors. He defeated Dana Quigley in a two-hole sudden-death playoff. In 2006, Roberts became the first golfer to open a Champions Tour season with three wins. Later that season he won his second senior major by beating Eduardo Romero in a playoff at the Senior British Open. He won the Byron Nelson Award for lowest average stroke total per round. In 2009, he won his 2nd Senior British Open title after beating Fred Funk and Mark McNulty in a playoff. He won a month later in August at the Boeing Classic, where he denied Mark O'Meara his first Champions Tour victory, defeating him by one stroke after making birdie on the final hole. The GWAA voted him Player of the Year. He broke the 54-hole tournament record for lowest score in relationship to par (25-under) and most birdies (26) as well as sharing lowest score (191). The marks were set largely due to scoring his career-best 61 in the final round of his 2006 MasterCard Championship at Hualalai win."
