When you look at the dosmetic records for the last 4-day championship there's an array of batsman who have been tried and failed (Devon Smith has 43 tests between 2003-18 with an average of 23.78 ). It's not a short term problem. Like @Aislabie says there is no stand out player. It took Rory Burns five seasons scoring 1000+ runs to get picked (probably 3 seasons too long). Sibley had nine centuries in two seasons before he got picked, he's already got two test centuries. We also have three keepers that'd probably get in most teams as a keeper or batsman. It's easy to judge other countries by the same standards. West Indies would be more improved by Joe Denly, Keaton Jennings and a handful of others that have been discarded by England right now.I did go and look back at Brathwaite's record over the last three years along with a look at how openers have fared in general. This most definitely is a lean period for openers with a few like Karunaratne, Warner, Markram looking unbeatable at home but unable to replicate it away. Some like Latham, Masood and Agarwal have fared very well at home and are decent away too. And then there have been the likes of Rory Burns, Elgar who do an adequate to decent job everywhere along with some anomalies like Jennings (bless him) and Tamim Iqbal who at the moment look better away than at home. And Brathwaite averages less than Campbell over the last three years! He has the likes of KL Rahul, Raval, Harris and Bancroft for company and given that none of them are first choice players now it shows how bad Brathwaite has been and how lucky he is that a lack of alternatives has kept him in the team.
I still think this team could easily do better, Chase and Dowrich for example have been adequate but can easily be better with more focus on their batting (their first-class records indicate that there is a lot more to come). A big problem is how pace friendly the pitches have become in recent times over at home. From looking at his overall record, Bonner just appears to be a Chase clone although he might have improved now (@qpeedore could elaborate perhaps). Hope's predicament of not playing a single fC game is the thing that reminded me of Mendis, for a long period he was just going through the motions in ODIs despite not having an actually decent domestic record and was never dropped to rectify it either.
I do think that a bit of coaching could improve their side. Will be interesting to see what Simmons does. Chase is okay-ish for a second spinner but when you have a spinner like Cornwall on the bench and a lack of batting prospects, it makes sense to ask the guy with a good record domestically and looks the part to be more of a batsman than a bowler.
It's why I could understand persisting with Hope (and even Campbell). I'd expect Moseley to get a shot sooner but Campbell got two centuries last season so it's not like he's out of form compared with others. Da Silva's runs have all come at 5 for T&T and he got his century opening in the practice match against a bowling line up containing none of the current first choice 4 bowlers. Maybe that will prompt him/selectors/coaches to move him to open but I wouldn't say it puts him in line to go into test cricket.
West Indies cricket seems to be going in the right direction for the first time in 20-years (barring the T20 success) so hopefully it's something that will improve.