Despite a whirlwind of activity -- and hasn’t that been fun? -- plenty of teams aren’t done with the heavy lifting. That is, they still have significant holes to fill, and with the free-agent market thinned out, filling them may require creativity.

While teams like the Yankees, Phillies, White Sox and Reds have gotten much better this offseason, there are several others clubs that are still seeking foundational pieces.

Here are five teams that still have important holes to fill and how they may go about filling them.

1. Nationals

Pay no attention to those vacancies at first base, second and third. General manager Mike Rizzo will fill them all at some point -- and he started with the bullpen, adding Will Harris. His first priority was re-signing Stephen Strasburg, and once he did that, the Nationals were positioned to win again thanks to arguably MLB’s best rotation. Still, so much uncertainty has to be a bit unsettling.

What to do: Re-sign veteran Ryan Zimmerman to play first and right-handers Daniel Hudson and Will Harris for the bullpen. Make top prospect Carter Kieboom the everyday second baseman, and if Josh Donaldson signs elsewhere, find a second-tier free agent (Todd Frazier, perhaps?) to fill the void at third in the short term. With all that pitching, the Nationals have the luxury to adjust the roster as the season plays out.

2. Braves

There’s a big hole in the middle of the lineup that has Donaldson’s name written all over it. If the Braves re-sign him, they might be the National League’s best team. If they don’t, well, they’ve still had a great offseason thanks to the additions of Cole Hamels, Travis d'Arnaud and Will Smith.

What to do: How about nothing? If Donaldson signs with another team, that might be the way to go. For one reason, GM Alex Anthopoulos has two interesting internal options in Johan Camargo and Austin Riley. For another, while the Braves have the prospects to make a serious run at trading for Kris Bryant or Nolan Arenado, to do so they would have to weaken the Braves in the area that makes them so formidable -- young pitching. Besides, there’s a good chance one or both of them will still be available in July.

3. Angels

No team has a more challenging few weeks than this one as the Angels continue their search for a No. 1 starter. Even with all the good work general manager Billy Eppler has done on the lineup (signing Anthony Rendon) and rotation (signing Julio Teheran and trading for Dylan Bundy) this offseason, the Halos are still not in position to challenge the Astros and A’s in the American League West. One more arm might just do that, but No. 1 starters may be the most coveted commodity in the game.

What to do: David Price might be precisely who the Angels need. The price will be high, but the Halos could offset the prospect cost by taking on a large portion of the remaining three seasons and $96 million on his contract. D-backs lefty Robbie Ray is another possibility, as are some of the unsigned free agents, such as Alex Wood or Ivan Nova.

4. Rangers

Arenado appears to be at the top of the Rangers' wish list after the Angels swooped in and signed Rendon. Arenado would not elevate Texas to the top of the AL West, but he’d put it in the conversation after general manager Jon Daniels dramatically improved his rotation with the additions of Corey Kluber, Kyle Gibson and Jordan Lyles.

What to do: Just do it. If Arenado isn’t an option, Bryant might be, as the Cubs are listening. Rangers third basemen ranked 26th in OPS (.699), 23rd in on-base percentage (.310) and 24th in home runs (19) in 2019 while playing at hitter-friendly Globe Life Park. Third base wasn’t the only problem area, but it would be a good place to start as the Rangers move to a beautiful new venue in Globe Life Field.

5. Cardinals

The Cardinals want and need an impact bat after finishing 10th in the NL in runs and 11th in OPS in 2019. At this point, they don’t seem motivated to re-sign Marcell Ozuna. If they’re interested in Nicholas Castellanos, they’ve kept it a secret. Instead, the Cardinals would prefer a left-handed-hitting outfielder -- Ozuna and Castellanos hit right-handed -- which is why Joc Pederson would be an ideal fit via trade. Unfortunately for the Cardinals, the Dodgers don’t seem motivated to trade him unless they’re overwhelmed.

What to do: Let’s pencil Arenado in at third base and call it a successful offseason. If only life were so simple. While the Rockies are listening to offers for their third baseman, it’s not clear that they’d actually pull the trigger on a trade. The Cardinals may lead the Majors in patience, which is why president of baseball operations John Mozeliak could bide his time and check their options during Spring Training and at the Trade Deadline in July.