The Rays finished 90-72 in 2018, their most successful season since 2013, and by all indications it was something resembling "real." What we mean by that is that unlike the 89-73 Mariners, who were outscored by so many runs that they actually looked like a 78-win team, the Rays' +70 run differential was the equivalent of an 89-win team. FanGraphs has a more complicated version (called "BaseRuns") that had the Rays actually showing the talent level of a 96-win team.
For all that performance, the Rays finished ... third in the American League East at 18 games behind Boston, and seven games behind the A's for the second AL Wild Card. Life in the AL isn't easy.
But that is life for the Rays, and they can't simply sit around and wait for the day that will never come where the Yankees and Red Sox are in down cycles at the same time. Based on what they have on hand right now, the respected Steamer projection system pegs the Rays as an 84-78 roster for 2019, one of the 10 best in baseball. Sure, that's worse than the Yankees, Red Sox, Astros, and Indians in the AL. It's not easy. It's not supposed to be easy.
Yet the way things are set up, it makes sense for the Rays to be aggressive. Their best hitter is Tommy Pham, who turns 31 in March. Kevin Kiermaier turns 29 in April. They swapped four years of Mallex Smith for two of Mike Zunino (plus a potential defensive upgrade in Guillermo Heredia), and AL Cy Young winner Blake Snell is as valuable right now as he'll ever be. They had the third-best ERA in baseball after they began using "the opener," and while a lot of that success was thanks to Snell, it wasn't all him. It feels like a window of contention -- or the "going for the AL Wild Card" version of that which exists in the AL East -- is opening, especially with Seattle taking a step back and Oakland hardly guaranteed to repeat.
That doesn't mean that they have to push all their chips in and trade top prospects like Wander Franco or Jesus Sanchez to try to win now. It does mean they should try to win, now, and with only about $35 million committed to the entire roster in 2019 (after designating C.J. Cron for assignment on Tuesday), they have ways they can do that which will fit into even Tampa Bay's budget.
There's not a ton of value in going from 65 wins to 70, or from 74 to 77. But there's a lot of value in adding another win or two or three at the level the Rays are starting from.
As you can see in the projections, the Rays have lots of depth, no stars and no massive holes. That means if they're going to improve, they're going to have to improve big. 

Let's help with some ideas.
1) Make the Cron move make sense by adding a better righty bat
Tampa Bay raised some eyebrows when it DFA'd Cron, who hit 30 homers with a 123 OPS+ in his only year with the Rays. (It was especially surprising because they had designated Corey Dickerson for assignment -- and later traded him to the Pirates -- to make room for Cron in February, and Dickerson ended up having a very good year with Pittsburgh.)
Now, that was far better than any year he'd had before, and he's a right-handed, defensively-limited first baseman/DH type in a baseball world in which those types of players are not highly valued. If you don't think he's repeating his 2018 line, or if you think a combo of Jake Bauers and Ji-Man Choi can approximate his value in 2019, you can see the idea here. 
But Cron was good last year, and his expected $5 million arbitration salary isn't exactly unbearable. To make this move make sense, they must use the cleared salary and roster spot to import someone better. In this case, that "someone better" is Nelson Cruz.

That's in part because he still slugs, with five straight years of 37 homers, and hasn't shown evidence of decline, as we investigated recently. But it's also because he's a DH-only player with few places to go; it's possible that only the Astros, Twins and Rays are interested in his services. That combination, plus his age, means he's getting a one- or two-year deal at most for a reasonable price. 
You might prefer Josh Donaldson, though his calf issues may mean he doesn't want to go to another turf field. Maybe you like Nicholas Castellanos, Andrew McCutchen or Jose Martinez. Those are all fine ideas, all good righty bats who fit in different ways. It just has to be someone. It can't be no one.  
2. Trade for Paul Goldschmidt
This won't be easy, of course. The Yankees, Cardinals, Astros and others would all be interested in one of the game's best first basemen, if it's true that Arizona would move him. He hit 33 homers with a .290/.389/.533 line in 2018, and his defensive reputation is strong.
We're including the Rays here -- and yes, this means moving Bauers or first base prospects Nathaniel Lowe or Joe McCarthy back to Arizona if that's what it takes -- because Goldschmidt is under contract for one more year at $14.5 million. Yes, the Rays can afford that in financial terms; yes, they can afford that in terms of prospects. Goldschmidt wouldn't come cheaply, but with only one year of control it might not be as much as you'd think -- maybe slightly better than the Manny Machado return -- and the Rays have what is likely a top-five farm system to deal from.

Suddenly, a lineup that includes Pham, Cruz and Goldschmidt in the middle, surrounded by Austin Meadows, Zunino, Kiermaier, Daniel Robertson, Matt Duffy and Joey Wendle looks like one you can win with.
3. Try to sign Snell to an extension
This doesn't improve the 2019 team in any way, but it's a good idea nonetheless. Snell can't be a free agent until after 2022, but he's clearly an elite pitcher and the best player on the Rays, so committing to him long-term is a strong idea. (Tampa Bay may have also learned a lesson from the Chris Archer trade, in which it did very well to add Tyler Glasnow, Meadows and Shane Baz, in part because of the contract Archer had signed.)
4. Sign a veteran starter, like Lance Lynn
Snell's a stud, Glasnow looks like he still could become one -- he cut his walk rate from 14 percent to eight percent after the trade -- and injured prospects Brent Honeywell, Jose De Leon and Anthony Banda could all contribute in 2019. There's Ryne Stanek, and Ryan Yarbrough, and Jake Faria, and Yonny Chirinos, and Jalen Beeks, and... it's not enough. Part of the reason they had to use the opener was because their starting pitching collapsed into a sea of injuries.
The Rays aren't likely signing Patrick Corbin, Dallas Keuchel, J.A. Happ or even Charlie Morton. But Lynn is intriguing, partially because he's durable -- outside of a missed 2016, he's appeared in 30 games in each full year of his career -- and partially because there's maybe more in there. Ignore his ugly 4.77 ERA, and focus on the fact that after his trade to the Yankees, his strikeout rate jumped (from 21 percent to 26 percent) and his walk rate dropped by half (from 13 percent to six percent).

What changed? This is an oversimplification, but there's clear evidence that he moved closer to the third-base side of the rubber just before the trade. The Rays have had success with this kind of player before. Maybe this is Giovany Gonzalez or Trevor Cahill or so on. But again: Someone. Get someone.
(There's an argument also to sign the injured Garrett Richards as the next Nathan Eovaldi, but that's a separate topic entirely.)
5) Trade for a quietly valuable reliever
With Sergio Romo in free agency, there's a very fun argument to make that they should trade for Edwin Diaz, because Diaz is incredibly valuable, may be available and it seems like Seattle and Tampa Bay make trades every other day. But that's not going to happen without extremely high-value prospects going back, and the Rays aren't going to go sign Craig Kimbrel, Adam Ottavino, Andrew Miller or Player Page for David Robertson.
So instead, let's turn to the trade market. Let's find a different AL West team that's not ready to contend and might be interested in turning their best reliever into more talent: Jose Leclerc of the Rangers.
It's OK if you don't know him, because pitchers who get 12 saves on last-place teams don't garner much notice -- not that saves matter (they don't). But he put up a 1.56 ERA, and by our most advanced Statcast™ quality-of-contact metric he was possibly baseball's second-best reliever, and you know a team like the Rays would value his elite fastball spin rate (99th percentile). He was so, so good last year, and he has four years of control left.
The Rangers need help pretty much everywhere. It wouldn't take Franco, but it would take a few good Tampa Bay prospects, along with Duffy, a pitcher or some combination. That's OK. Adding Leclerc to Stanek, Chaz Roe, Jose Alvarado, Diego Castillo and what's sure to be a sea of others is a deal worth making. If the Rays are going to "bullpen" and "opener," you need a ton of relief talent to do it. There are many ways to do it. This is one of them.