These things are often perception, right?
I agree with most of your second paragraph. Where I differ is that I think their approach was part of the plan. In general, I think part of their plan has always been to work young players in slowly, focusing on putting them in position to succeed. I think they entered the season with a mindset of having plenty of veteran parts, enough to keep them going until the young pieces sort themselves out.
Gallo is actually an interesting case in point. He became the favorite target of dissenters here, even though he ended the season with an OPS+ almost exactly at the league average. Folks will point to him doing most of his damage in April, which is true, but I think they got exactly from him what they were wanting. They used him to buy time as they sorted out which of Wallner, Larnach and, to a lesser extent, Kirilloff was going to be productive. The sense among many posts about Gallo is that he was starting every day until they benched him late, but the reality is that as early as June, he was only starting half the games and coming in regularly for defense.
Wallner was the guy who came through, and he was excellent. It's easy for folks (and many have) to say, "See, Wallner's OPS+ is 139. They should have brought him up much sooner." How about considering that potentially (I would say, likely) one of the reasons he played so well is that they didn't bring him up sooner? With the extra seasoning he got in AAA and the ability to use a guy like Gallo to absorb at bats while gradually working Wallner into the mix, he was able to taste success and thrive.
I could post a separate post describing how I thing your last sentence is one of the key tenets of the FO's approach. They are not going to make a lot of major moves. They are also not going to box themselves in by trying a lot of moves that are attempts to massively move the needle, but become millstones when they don't.
Rather, they are going to make a lot of moves that nudge the needle, and they are going to recognize the interconnectedness of those moves. Gallo was a needle-nudger, buying time for rookies, as I described. Solano was a needle-nudger, buying time and flexibility for Julien to develop and to cover injuries (in this case, Polanco). Farmer -- needle-nudger, Castro -- needle-nudger, both buying flexibility. It just so happens that several of those needle-nudgers not only bought time and flexibility, they continued to perform well. At some level, even Correa was a needle-nudger, in the sense that they didn't buy in until it came on their terms (only six years).