Mateo built a Japanese-style mound at his house to help with his training after the 2016 season.
Source: Sponichi 1/22/2017
May 12 vs Hiroshima at Mazda Stadium – Mateo walked in three consecutive runners in the seventh inning. Mateo entered the game with a runner on first and second and no out in the seventh inning. He gave up a single to load the bases before allowing a run to score on sac fly. A walk and an infield pop out later, he walked in three consecutive runners.
Mateo is the seventeenth player in NPB history (ninth in the Central League, eighth in the Pacific League, fourth Hanshin, first foreign pitcher in the Central League) to walk in three consecutive runners since the start of the two-league format. The NPB record of four was set by Takeo Mizobe on April 20, 1947.