Josh Harrison is one of several players on the verge of losing his starting spot. (USATSI)
Josh Harrison is one of several players on the verge of losing his starting spot. (USATSI)

Aside from untimely injuries (untimely like on a Monday evening after lineups have been submitted), the most frustrating circumstance for Fantasy owners is being unaware of starting players losing their jobs and not boasting a suitable replacement.

Poor production and impending returns from the disabled list and rehab stints always have pitchers and hitters on the verge of losing their jobs. Such is currently the case around both leagues. It's time to examine those who are not long for their spots. The following hitters are on the endangered list:

Daniel Nava (Boston): Nava might have received a short stay of execution when Shane Victorino suffered what appears to be a small setback in his recovery from a fractured left foot at Triple-A Pawtucket. But he has been thoroughly outperformed by Brock Holt, which means his playing time should be severely cut upon the return of Victorino. A stat line of .202/.295/.298 does not warrant a starting position.

Josh Harrison (Pittsburgh): On the other hand, there's Josh Harrison, who has earned a starting spot, but will have no place to play once second baseman Neil Walker returns from the disabled list. Harrison was already pushed out of the outfield when Gregory Polanco was promoted. His only opportunity to start would be at shortstop, but Clint Hurdle is quite unlikely to risk that big of a defensive hit. Hurdle has stated that he will need to find at-bats for Harrison, but Fantasy owners will not and should not stick Harrison in their lineups when he is destined to play three or four games a week.

Justin Turner (Los Angeles Dodgers): Nothing is breaking well for Turner these days aside from his continued production at the plate when he does get a chance to play. A calf injury has limited him to pinch-hitting, but he has even done that well. Turner owns a .293/.344/.414 stat line that arguably warrants him keeping the starting spot when Juan Uribe returns from a rehab assignment that is set to begin Sunday. But Uribe produced excellent numbers before going down and is not about to lose his job to injury.

DJ LeMahieu (Colorado Rockies): This is a no-brainer - and only desperation and one heck of a deep league would have forced any Fantasy owner to pick up this guy. Not that LeMahieu is terrible, but he doesn't have the pop normally associated with a corner position, as his two home runs in 217 at-bats can attest. He is playing mostly at second base, which is fine, but when Nolan Arenado returns, LeMahieu could wind up on the bench behind impressive Josh Rutledge. Just something to keep your eye on.

Will Venable (San Diego): Venable failed to carry the momentum he gained in the second half of 2013 into this season. He slugged 11 home runs with 14 doubles and 13 stolen bases in his last 59 games a year ago, but slumped early in 2014 and continues heading in the wrong direction with just two hits in his last 20 at-bats and a stat line of .205/.274/.288 that is pathetic for a corner outfielder. With top prospect Jake Goebbert tearing it up at Triple-A and a Padres team desperate for hitting, Venable is likely destined to ride some pine.

There are others, of course. The return of Corey Hart should result in Endy Chavez returning to a better-suited utility role in Seattle, and Cody Ross will likely be pushed aside when Mark Trumbo comes back from a foot injury.

Fantasy owners need to be aware of these developments now or they will be lamenting later. One can't be caught with lineups featuring players not playing.