I'm not really someone who thinks that an MLB manager is important, so I don't want to sound like I'm defnding Shelton, but I really wouldn't draw many conclusions about him based on this year. 1) the team is bad – it's mediocre in a number of ways on paper but the guys who would lead it to that mediocrity are either hurt or underperforming; 2) more importantly, it seems patently clear that the organization doesn't care about winning games; 3) it also seems somewhat clear that there's a plan in place to get certain guys looks for certain roles.
I'm not 100% sure about #3 yet, but the other two prevent me from really making many strong decisions. I think the basic approach is that this is one long exhibition. I don't think we're trying to lose in the conscious way that we joke about with memes, but I also don't think he's really doing much more than executing certain decisions with the bad personnel that he has. I think the smart money is that if the offense wasn't total garbage, we'd have a few more wins under our belts but otherwise that's it.
At the end of the day, I don't think MLB managers make a huge difference, so I don't have a strong attachment to Shelton one way or another. My basic take would be that next season is the year where several players, as well as maybe him, are probably auditioning for a role going forward. Having the culture of an exhibition that values process over results isn't ideal for trying to build a winner in the near range, but I think the 2020 season will end up being mostly a wash.