As an amateur wrestler, Cobb represented Guam at the 2004 Summer Olympics, where he became the nation's flag bearer in the opening ceremony and competed in the men's light heavyweight freestyle category.

Cobb qualified for the Guamanian squad in the men's 84 kg class at the 2004 Summer Olympics in Athens by receiving a continental berth from the Oceanian Championships in Dededo.

[6] He received two straight losses due to technical superiority and no classification points in a preliminary pool match against Cuba's Yoel Romero and Germany's Davyd Bichinashvili, finishing 21st overall out of 22 wrestlers.

[11] Matanza remained undefeated until April 9, 2016, when he was pinned by Rey Mysterio in an Aztec Warfare match, losing the Lucha Underground Championship in the process.

On October 20, The Chosen Bros defeated the Lucha Brothers (Rey Fenix and Penta el Zero M) to win the PWG World Tag Team Championship.

[citation needed] On October 19, Cobb defeated Walter at Smokey and the Bandido to win the PWG World Championship.

[citation needed] On May 27, 2017, Cobb made his Progress Wrestling debut by defeating Nathan Cruz in the first round of the Super Strong Style 16 Tournament 2017.

On November 6, 2017, Cobb was announced as a participant in New Japan Pro-Wrestling's 2017 World Tag League, where he would team with Michael Elgin.

Cobb spent the bulk of late 2018 participating in the World Tag League tournament with partner Michael Elgin, winning eight matches, but failing to qualify for the finals.

In August 2020, Cobb competed in the New Japan Cup USA where he defeated Tanga Loa in the first round before losing to Kenta in the semi-finals.

On April 9, O-Khan and Cobb became the IWGP Tag Team Champions for the first time in both men's careers, during the Hyper Battle series.

[33] After losing the titles at Forbidden Door, Cobb was announced to be a part of the G1 Climax 32 in July at Dominion 6.12 in Osaka-jo Hall, where he would compete in the A Block.

[35] Later that year in October, Cobb participated in a tournament to crown the inaugural NJPW World Television Champion, but was defeated by Yoshi-Hashi in the first round.

[36] The following month at Battle Autumn, Cobb and O-Khan faced FTR in a rematch for the IWGP Tag Team titles, but were defeated.

[43] Later in the month, Cobb competed on the buy-in of Forbidden Door, where he teamed with United Empire stablemates, Kyle Fletcher and TJP in a losing effort to Los Ingobernables de Japon members, Shingo Takagi, Bushhi and Hiromu Takahashi .

[47] On October 14 at King of Pro-Wrestling Cobb lost the World Television title to Ren Narita in a 3-way match that also includes Yota Tsuji.

On July 21, 2018, Cobb made his Ring of Honor debut by attacking Eli Isom and FR Josie at a television taping.

At Death Before Dishonor XVI on September 28, Cobb confronted Punishment Martinez following his defense of the ROH World Television Championship.

[49] Cobb made his debut for All Elite Wrestling (AEW) on the February 12, 2020 episode of Dynamite, attacking Jon Moxley alongside The Inner Circle.

[54] On the March 29, 2023 episode of Dynamite, he challenged Kenny Omega for the IWGP United States Heavyweight Championship, in a losing effort.

[55] On the May 15, 2024 episode of Dynamite, Cobb teamed with Kyle Fletcher, in a losing effort against Blackpool Combat Club (Bryan Danielson and Jon Moxley).

[57] During his work in Lucha Underground, Cobb performed as "The Monster" Matanza Cueto, wearing a mask and a boilersuit.