Column: Mike Trout’s injury scare is a reminder that Angels’ roster isn’t deep

The play was classic Mike Trout, taking an extra base while an outfielder fumbled his single to center field.

Except that when Trout popped up from his slide, he called for time, limped off the bag and …

Gulp.

His left calf was cramped.

“That’s what scared me,” he said.

The discomfort vanished and Trout remained in the game, but the alarming eighth-inning episode was an uncomfortable reminder of how dependent the Angels are on him and a handful of other high-level performers. They can’t afford to lose any of them and they’re already down a few.

The glaring lack of depth and absence of any margin for error was on display in their season-opening 4-0 loss Thursday to the division rival Athletics at the Oakland Coliseum.

“Obviously, it was the first day, so everybody was anxious to get out there,” the ever-upbeat Trout said. “The good thing is we have a game tomorrow too.”

He’s right — to a degree. This was only one of 162 games, but what made it problematic was how they lost. The team’s projected shortcomings were their shortcomings in the opener.

A quick glance at the Angels’ own stadium in Anaheim is indicative of how the team expects to win games this season. The four giant images above the ticket windows to the sides of the Home Plate Gate feature only hitters.

Two are on the injured list.

Shohei Ohtani’s absence was expected. Justin Upton’s wasn’t; the four-time All-Star sprained a toe in the Freeway Series.

A team that was designed to outslug its opponents suddenly looks as if it doesn’t possess the necessary firepower to do so.

The Angels were limited to three hits, including one over the six innings pitched by the A’s unremarkable starter, Mike Fiers. They didn’t collect their first hit until Tommy La Stella doubled in the fifth inning. About as close they came to scoring was in the fourth inning, when Trout was on second base and Andrelton Simmons drove a ball to the warning track that was caught by a sky-bound Robbie Grossman.

To contend for a wild-card berth — the Houston Astros should win the American League West — the Angels will have to survive this period. How long it will last is anyone’s guess. General manager Billy Eppler said he didn’t have a timetable for Upton’s return. Ohtani isn’t expected back for another five weeks.

And the Angels are certainly not in position to win many low-scoring games. Their opening day starter, Trevor Cahill, notched 18 wins … in 2010.

Cahill was a respectable 7-4 with a 3.76 earned-run average for the Athletics last season, but advanced metrics indicate he benefited from good defense and good fortune. The Angels can provide him with defense, but they have no control over his fortune.

He pitched six innings Thursday, but was charged with four runs and six hits. He was particularly vulnerable to extra-base hits. Jurickson Profar tripled to right field in the second inning and scored the first run. Stephen Piscotty’s third-inning double drove in Grossman. Marcus Semien homered in the fourth inning and Khris Davis did the same in the sixth.

What the Angels require from Cahill is what they will require from all of their starters: the best-case scenario.

In the cases of relatively inexperienced starters such as Felix Pena and Chris Stratton, they will need them to reach new heights. Or, in the case of Matt Harvey, they will need him to recapture past glory.

But similar to the lineup, the rotation has already absorbed a crushing blow. Andrew Heaney, who made a team-high 30 starts last season, is out with an elbow injury he sustained earlier in the month. He experienced a setback in his recovery this week.

The tightrope on which the Angels are walking has become even less stable.

The story is the same with the bullpen, where the Angels are relying on closer Cody Allen to recover from the worst season of his career. Allen posted a 4.70 earned-run average with the Cleveland Indians last year.

It’s little wonder Eppler was evasive when asked if his team would reach the postseason.

“Time will tell,” the general manager said.

Playfully told to show confidence in his team, Eppler repeated, “Time will tell.”

Eppler was reminded how hard he worked to construct the roster.

“I like our club,” he said. “If we’re the best version of ourselves, day in and day out, good things will happen.”

The Angels couldn’t be the best versions of themselves in the opener because they weren’t all on the field. They can’t have many more days like this.

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dylan.hernandez@latimes.com

Follow Dylan Hernandez on Twitter @dylanohernandez