From 1985 to 1986, Arce played for Deportivo Jalapa in Guatemala. From 1988 to 1991, Arce played for Dragon in the Salvadoran second division, where he was the league's leading scorer in the 1991–92 season with 21 goals. Playing for Dragon, in two seasons in first division, "Ignacio Raul" scored 34 goals (13 in 1989–90 and 21 in 1990–91), in the second season he was the scoring champion of the regular season when he played four laps. He then moved up to play for
C.D. Luis Ángel Firpo of the Salvadoran first division from 1991 to 1996. Here he was the league's top scorer three season in a row (1993–1996) with 24, 21 and 25 goals, respectively. In Luis Ángel Firpo he scored in five seasons with a total of 119 goals. These early achievements earned him a spot in the national team and a move to the United States.
D.C. United In 1996, Diaz Arce signed with
Major League Soccer, and was drafted tenth overall in the
MLS Inaugural Player Draft by
D.C. United on February 6. On April 20, Diaz Arce recorded the first goal in D.C. United's history when he scored in the 7th minute against the
LA Galaxy. Diaz Arce was also the first player in MLS history to score a hat-trick in postseason play. He scored 3 against the Tampa Bay Mutiny on October 10, 1996. DC United won 4-1 and went on to become the first MLS champions. Diaz Arce continued to perform well in his second season, registering 15 goals, and helping D.C. United to win their second consecutive
MLS Cup.
New England Revolution Salary cap pressures and reported conflicts between Diaz Arce and
Marco Etcheverry, resulted in D.C. trading one of the league's most prolific scorers to the
New England Revolution. The deal was not well received by D.C. United's fanbase. On February 5, 1998, in what would become the first three-team trade in MLS history, New England acquired Diaz Arce from D.C. United in exchange for
Alexi Lalas and a second-round pick in the
1999 MLS College Draft, which were traded to the
MetroStars with the MetroStars' second-round pick in the 1999 MLS College Draft and future considerations going to D.C. United along with New England's first-round pick in the 1999 MLS College Draft. Diaz Arce made his Revolution debut in the first match of a season, a loss to his former club, on March 29, 1998. He scored his first Revolution goal the following match, in a 2–1 defeat to the
Miami Fusion on April 4.
End of MLS career Nevertheless, Diaz Arce was traded again, and eventually played for the
Tampa Bay Mutiny and
San Jose Clash, as well as briefly with the
MetroStars, registering 13 goals and 7 assists in the 1999 season. Diaz Arce continued to be shuttled around in 2000, playing for Tampa Bay and D.C. again in 2000, and scoring a career low 9 goals. Diaz Arce continued to decline in 2001, playing only briefly for D.C. United, before being traded again to the
Colorado Rapids, with whom he ended his career in MLS. Diaz Arce left MLS second in career goals scored with 82, behind only Roy Lassiter; although he has fallen as others have surpassed both of their totals.
Charleston & Puerto Rico For the 2002 season, Diaz Arce played for the
Charleston Battery of the
A-League, scoring 6 goals and 4 assists in 1319 minutes. He was not the success Charleston had hoped for, however, and left following the year. In 2004, Diaz Arce joined the struggling expansion
Puerto Rico Islanders, and gave the team a significant boost, scoring two goals in his first game and a total of 7 in 1233 minutes, and helping the team attain a level of respectability. He is now the U.S. Soccer Development Academy Director at the Chicago Magico Soccer Club. ==International career==