Thankfully it is not foolproof way to build a playoff team or it would become a serious problem in the league.
San Diego was mentioned in the comments, they (on paper) totally revamped their roster heading into 2015 build to win but failed horribly. Colorado was mentioned in the comments but have annually had a top offense but cellar dwelling starting rotation. The Coors Field effect means you have to home-grow your pitchers and they are doing that. It's unfair to label them "issue" teams.
We do not and will never have 30 potential playoff teams to start the season. As a fan all you can ask for is a clear direction. I'm okay knowing that Milwaukee has already bowed out of the NL Central race but not okay that Cincinnati has bowed too but aren't taking any measures to improve.