The phrase "slightly implausible" is correct and usable in written English.
You can use it to describe a situation, idea, or claim that seems somewhat unlikely or hard to believe, but not completely impossible.
Example: "While the theory was interesting, it was ultimately deemed slightly implausible by the experts in the field."
Alternatives: "somewhat unlikely" or "marginally unbelievable."
It was all slightly implausible.
There's something slightly implausible about "The Right Honourable Grant Shapps", as he was introduced on Sunday.
Talking of dark, conspiratorial forces, there's a delicious – if slightly implausible – theory about Hoffenheim's descent to hell doing the rounds.
Zoolander hooked onto that slightly implausible fashion moment to spin out a fantastical plot of attempted assassination, accented with lots of slapstick.
The slightly implausible aim of the game is to become a wine baron, investing in one of 10 French wine regions.
And above all there is Thomas Haden Church, suavely stealing scenes from Mr. Quaid in the slightly implausible but nonetheless charming role of Lawrence's ne'er-do-well adoptive brother, Chuck.
Then for others still, it was some slightly-less-implausible concession like a one-year delay of the individual mandate; for others, it was something actually plausible like the delay of the medical device tax or the Vitter Amendment; for others (the Marlin Stutzman caucus, if you will), it was just some kind of concession, some kind of scalp to hold up to their constituents.
It must be acknowledged that we used routine data, so missing and implausible data could not be avoided in some cases which resulted in a slightly reduced sample.
The rankings are slightly different (but still very similar) in the case of TO, and quite different in the implausible scenario (see the discussion above) of NPO.
But Haenel's blank, slightly bug-eyed solemnity gives no sense of her inner life; the parade of minor figures is mostly implausible, and the climactic revelation is melodramatic and unsatisfying.
A couple of times I feel as if we are in a slightly overwritten two-hander, and I have the strong sense that any audience would find the mounting intensity a bit implausible.
