Who's on first? For Yankees, that won't be so easy to answer

With Mark Teixeira hobbled and not hitting, and Greg Bird out for the season, the Yankees have a weakness where they once had a strength. What's next? USA TODAY Sports, Getty Images

NEW YORK -- In an ideal world for the New York Yankees, Mark Teixeira would be having a monster year, contributing to a winning team and making himself very attractive in free agency this winter.

Meanwhile, top first base prospect Greg Bird would be growing in Triple-A, fleshing out all aspects of his game before confidently assuming the starting big league job in 2017.

But the Yankees don’t live in an ideal world, which is why what once looked like a strength, with an obvious succession plan, is now a question mark.

Both Teixeira and Bird have been injured. The Yankees lost Bird before the season to shoulder surgery, preventing him from building on his .261 average, 11 home runs, 31 RBIs and .872 OPS in 46 big league games last year. Teixeira, who is scheduled to return from a knee injury on Saturday, has looked more like a 63-year-old player than a 36-year-old one. Teixeira is hitting just .180 and hasn’t swatted a homer in a career-worst 141 consecutive at-bats. A year ago at this time, Teixeira was an early AL MVP contender with a .926 OPS. His current OPS of .535 is among the worst in baseball.

Once Teixeira rejoins the team, the future of the Yankees at first base could become clearer. For his part, Teixeira needs to show he can still play. While he is still a plus-fielder, he must hit more to justify a starting job somewhere next year. If he can play the way he did for the first four months of last season, the Yankees could consider giving him the qualifying offer this winter, with the aim, should he accept, of providing protection for when Bird returns to action. Teixeira could also decline the one-year deal and seek a multiyear contract elsewhere, which would allow the Yankees to collect a compensatory first-round pick.

Admittedly, this is a lot to ask for, because Teixeira -- albeit historically a slow starter -- hasn't shown signs of a turnaround.

Bird, 23, remains mostly an unknown. Of all the positions on the field, first base is the one least likely to be impacted by a shoulder injury, although it's still anyone's guess how the surgery will affect him at the plate. Still, the Yankees may have to roll the dice on Bird next year. He looked good in 2015 replacing an injured Teixeira, and basically matched his production with a swing perfectly suited for Yankee Stadium.

That doesn't mean he's proven himself, though. The struggles of righty Luis Severino -- currently back at Triple-A after starting the season 0-6 with a 7.46 ERA -- is the latest cautionary tale that a nice, short rookie run doesn't guarantee success in Year 2.

While the Yankees won't make any decisions until the winter, it seems likely they will move on without Teixeira and hand the first base job to Bird. It's in the Yankees' best interest to get younger and attempt to build a solid foundation before Bryce Harper and the potentially historic free-agent class of 2018 become available.

This offseason, the free-agent class is weak. That, along with Hal Steinbrenner's desire to lower payroll and create more financial flexibility, means the Yankees will have to get better from within.

Many Yankees fans seem ready to watch the kids play for a few years instead of suffering through the same, boring cycle of veteran Band-Aids. Coming off an injury, Bird won't be the perfect choice, but he's the most likely one.