Monteagudo was traded along with Chris Coletta from the Angels to the Phillies for Denny Doyle at the Winter Meetings on December 6, 1973, completing a transaction from four months earlier on August 14 when Philadelphia purchased Billy Grabarkewitz's contract from California.

[1] In seven seasons, Monteagudo compiled a 3–7 record with 58 strikeouts, a 5.05 ERA, four saves, and 132 innings pitched in 72 games (65 as a reliever).

Monteagudo also played 20 seasons in the Venezuelan Professional Baseball League with five teams: Caracas (1963–68), Magallanes (1968), La Guaira (1968–74, 1976–82) and Portuguesa (1975), compiling a 79–81 record with 897 strikeouts and a 3.37 ERA.

On December 20, 1973, Monteagudo kept the Cardenales de Lara hitless for 8+2⁄3 innings until Faustino Zabala ruined the no-hitter with a single to center field.

At the same time, Monteagudo played in the Mexican League with the Puebla, Coahuila, Aguascalientes and Veracruz clubs.