Inbox: Reinforcements on the way to rotation?

DENVER -- This week's Edward Jones Inbox comes at a celebratory time, as Rockies fans take a deep breath after Nolan Arenado's game-winning, cycle-completing homer to for a 7-5 victory over the Giants on Sunday at Coors Field.
I'm pretty sure there is only one question to ask after that. How the heck do ya follow that up!! @MileHiPhil

Now that's a good one. But here's the problem: With all the drama of the four-game sweep of the Giants and the five-game win streak, the Rockies will enter Tuesday just one game ahead of their opponent -- the D-backs, who have won seven straight. And by the way, the Dodgers, whom the Rockies will meet in a road series starting Friday, entered Monday's game with the Mets tied with the D-backs.
Rather than worrying about an encore, the Rockies will spend their time making tough rotation decisions and assessing needs, with the bullpen possibly being one. That leads to other questions.
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With Tyler Anderson, Jon Gray and Chad Bettis coming back, what do you think will be the rotation the Rockies will trot out when everyone healthy? @Jhobbs2244

I usually delay answering this question, but after Gray throws Monday night for Triple-A Albuquerque, he and Anderson (who pitched Sunday for Albuquerque) will be in that 70-pitch range and will at least be candidates to return to the rotation. It's hard to imagine at least Gray not being immediately back in the rotation. The team had trust in Anderson -- especially after four solid-to-stellar starts before his last outing -- when his knee issue flared. Bettis just threw his first full-distance bullpen session, so his return isn't imminent.
Righty Tyler Chatwood has been tremendous on the road and iffy at home, but the Rockies would have a hard time pushing their most experienced starter out of the rotation. Righties Antonio Senzatela (9-2, 4.10 ERA) and Germán Márquez (5-3, 4.19) have endured hiccups lately, but have good arguments to stay. No reason to displace lefty Kyle Freeland (8-4, 3.42) or righty Jeff Hoffman (4-0, 2.25).
My expectation remains that the Rockies will monitor health and use the 10-day disabled list so they have everyone either on the team or available in short order.
Love our batch of starting pitchers, but do you think we'll need to trade for a bona fide No. 1 to match up with other teams in the playoffs? @littlebailey24

I'll group this with another non-waiver Trade Deadline-related question:
Which prospects are untouchable, or at least unlikely to be used in trades at the Deadline? @RoxRake 

For now, I'd rather see them use their trade chips to improve the bullpen, as suggested in a series of tweeted questions from @JustinHobbs. The relief staff was taxed during the Giants series, and depth is a question.
Under general manager Jeff Bridich, the Rockies have been more inclined to trade players who reach the Majors than significant prospects. (Pitcher Eddie Butler to the Cubs for prospect pitcher James Farris, and outfielder Corey Dickerson, along with lower-level prospect infielder Kevin Padlo, to the Rays for reliever Jake McGee and righty Marquez are trades that come to mind.)
The problem is the season has shown Colorado that it needs its depth. Raimel Tapia has helped already in the outfield, and it's hard to part with, say, Ryan McMahon (excelling at Triple-A), when every infielder on the 40-man roster is in the Majors.
Ideally, dealing a lower-level prospect for a proven reliever -- like the 2009 deal that brought Rafael Betancourt from the Indians for pitcher Connor Graham, who didn't advance beyond Double-A, makes sense.