But they already are "true contenders." Everybody has holes. The Nats have one in RF at the moment.
They aren't going to sell the farm for rentals so there's no point in really worrying about it. The Eflin debate, to me, is a fun theoretical discussion that, thus far, is based entirely on the fact that the Phillies, according to the rumor, are NOT willing to trade him.
Modest acquisitions, or controllable acquisitions, are much more likely. But Machado is a special case. It's an easy call, really. If the Brewers or Yankees or Dodgers are out there with a really great offer, "nice talking to you, Orioles. Let's move on to Britton" (he should be cheap). But if the true market for MM is more along the lines of what was given up for Martinez or Darvish they should still be in on him. It's not just the Eflin rumor - every rumor you read about every team is usually about the guys teams won't trade.
And the team does still lack stars, even potential stars. Herrera still seems likely to be the same guy he is almost every year (he is actually incredibly consistent). Hoskins probably is one, but his profile is still limited as a righthanded 1B/LF. Kingery might not hit his stride - or even be allowed to settle into a full-time position - until 2020. Ditto Crawford who everyone just hoped would be a very good defensive player with high OBP, also not a star. Altherr and Williams are both probably solid major league players who would be fine (Altherr not at the moment, but overall) on a team getting more production/power from the IF.
Not that you need a bunch of stars, like I said, even this team is already a contender, but there aren't any on the way. One (whether it is Machado or Harper or someone else) will really move the needle.I don't really care if they go crazy upgrading to win in 2018, I'd settle for the WC or an NLDS loss and call it a learning experience just like the 2007 Phillies and the 2015 Astros. But I expect them to win in 2019-2020 and in that sense Ed is right, there's nobody in the minors who's really going to play a role that soon (position player-wise). They still don't have the young, dangerous homegrown core the Cubs and Astros did.