Race Comment Explainer

Original comment with matches highlighted:

prominent, ridden and chased leaders before 2 out, soon un-in, kept on one pace run-in

Matched phrases & meanings

Phrase	Meaning
kept on one pace run-in	The horse maintained its existing speed through the final run to the finish line, but could not accelerate or quicken relative to the leader.
Chased leaders	Running directly behind the horses in front of the field.
Outpaced	Could not keep up with faster horses mid-race.

Summary

The horse maintained its existing speed through the final run to the finish line, but could not accelerate or quicken relative to the leader.
Running directly behind the horses in front of the field.
Could not keep up with faster horses mid-race.