Falter may be a one, maybe two times through the lineup pitcher until he improves his secondary stuff.
His high FB does fool hitters, but eventually they get used to his extension, he needs to change up things the second time through the order. They are working to add a little velo, at 92-93 instead of 90-92 he'd be more effective.
The 5th starter may end up being Falter/Nelson/Valesquez/Strahm, that is, 2 or 3 long relievers pairing to get through 6 innings. At least until one of Painter, Abel, or some other arm emerges from the minors after the Allstar break.
Ranger if healthy is fine, people forget how good he is when he's on.
If Walker can consistently throw that splitter, he'll be fine, that's a nasty pitch that sets up a good but not great FB.