Houston Astros ace Justin Verlander left his spring training start on Sunday early because of a strained lat. On Monday, manager Dusty Baker said that Verlander doesn't feel the injury is as bad as the strained triceps he suffered in 2015, when he was sidelined for two months, but nonetheless Verlander will be shut down for the time being. The Astros should be concerned about any development that threatens his availability and effectiveness because, for all the talk about how Houston's scandal-riddled winter could cause the team to underperform, the more tangible risk involves the Astros' imbalanced rotation.  

At first blush, that assertion sounds silly. The Astros rotation is led by Verlander and Zack Greinke, two future Hall of Famers who have defied Father Time with their durability and their production. Verlander has topped the 200-inning threshold in 12 of his last 13 seasons, and has accumulated a 2.45 ERA in 73 starts since joining Houston in late 2017. Greinke has reeled off three 200-inning seasons in a row, and in 2019 set a career-high in strikeout-to-walk ratio. It would be fair to quip that any rotation fronted by those two would look lopsided in some way. 

Alas, Houston's potential rotation issues extend beyond trivia and accolades. The Astros lost significant depth over the winter: Gerrit Cole, Wade Miley, and Collin McHugh each left through free agency, and Aaron Sanchez was non-tendered due to his shoulder injury. The Astros did not add reinforcements through free agency or trade, either: Austin Pruitt, with 10 career starts in 67 appearances, represents the closest thing the Astros added to a veteran starter.

The Astros' inactivity puts pressure on the rest of their rotation, which includes Lance McCullers Jr., Josh James, and Jose Urquidy. While each of the three is talented, and could soon justify management's faith, their past workloads provide reason for caution. McCullers missed last season due to Tommy John surgery, and neither James nor Urquidy has ever thrown more than 150 frames. The Astros have finished second in the American League in starters' innings the past two years, but it would be an upset if that streak continued in 2020.

For perspective on how the back end of Houston's rotation stacks up against other contenders, take a look at this table:

TeamMax No. 3 starter inningsMax No. 4 starter inningsMax No. 5 starter inningsAverage




































There you see all the other probable postseason teams (defined as having at least a 50 percent shot at reaching October, per Baseball Prospectus) and the maximum number of innings their No. 3 through 5 starters (as forecast by Roster Resource) have thrown in the last three seasons, as well as the average of that number.

The only teams in Houston's neighborhood are the New York Yankees and Los Angeles Dodgers. Good company ... except for a catch in both directions. 

The Yankees have already suffered injuries to two of their top starters, in Luis Severino (out for the season) and James Paxton (at least a month), and are without Domingo German after he violated the league's domestic violence policy. This is, presumably, the floor for the Yankees.

The Dodgers, conversely, are where they are due to strategy. They traded for David Price, signed Alex Wood and Jimmy Nelson, and have been careful with how they've deployed Julio Urias. The other main difference between the Dodgers and the Astros is that Los Angeles has ample prospect depth, in the form of Dustin May, Tony Gonsolin, and even Josiah Gray.

Few teams can match that surplus, and the Astros aren't an exception. To wit, FanGraphs' Astros prospect list featured two players with future values above 50: Forrest Whitley and the aforementioned Urquidy; just three other pitchers graded above a 40, and one (Bryan Abreu) is a reliever. (PECOTA is more bullish on the Astros' pitching depth.) Even Whitley is coming off a season so poor that he carries a higher degree of volatility than his prospect ranking indicates.

Beyond Whitley, the Astros have a lot of names to sort through, each with their own notable blemish. Cionel Perez barely pitched last season; Cristian Javier is too sloppy with his geography (4.7 BB/9 rate across three minor-league levels in 2019); Rogelio Armenteros and Cy Sneed may not have the arsenals to make it work for long; and so on. You can nitpick the next wave in the system -- Enoli Paredes, Luis Garcia, Nivaldo Rodriguez, Brandon Bielak, Tyler Ivey -- just as easily, though we won't here. It's possible that, as James and Urquidy did before them, one or more of the above develops in an unexpected way. It would be an error to mistake that chance for a certainty, considering that the league is full of pitchers with similar profiles who did not make the leap to "good starter." 

Which brings us back to the importance of Verlander and Greinke. The Astros need both to remain healthy, or else risk setting off a chain reaction that will see them overexpose the rest of their starters, their depth, and their bullpen. (The same bullpen that lost Will Harris without replacing him.) The good news for the Astros is that Verlander and Greinke appear invincible. The bad news is that you don't have to look too far back in history to recognize the fleeting nature of the veteran workhorse starter. Take last decade's Philadelphia Phillies. Roy Halladay and Cliff Lee were both in their mid-30s, and seemed destined to pitch forever. Halladay followed up six consecutive 200-inning seasons with a rough and truncated 2012. He then threw 62 poor innings in 2013 and that was it for him. Lee was in his typical All-Star form in 2013. He threw fewer than 90 innings and was finished after 2014, that despite having previously pieced together six 200-inning years in a row.

Obviously what happened with Halladay and Lee has no bearing on what will happen with Verlander and Greinke. It is a reminder, however, that even the seemingly special starters break down over a long enough timeline. Verlander's injury could prove to be a minor blip in six months' time, and the Astros could well ride him and Greinke to another division title. But a setback or another injury down the road could have major ramifications, and could lead to a disappointing season in Houston.