* "la amiga de Anthony baja" - Anthony's friend goes down (in the sense of descending, or maybe "goes down" in the sense of being "down" in the mood).
* "la amiga de Anthony bajó" - Anthony's friend went down (in the sense of descending, or maybe "went down" in the sense of being "down" in the mood).
It's important to have the full context of the phrase to give a more precise translation.
For example, if someone said "la amiga de Anthony bajó al sótano" (Anthony's friend went down to the basement), the translation would be different from "la amiga de Anthony bajó el ánimo" (Anthony's friend's spirits went down).