SAN DIEGO -- Fifteen months ago, a dejected Dinelson Lamet sat atop the bench in the Padres' dugout before an April game at Petco Park. The right-hander had torn the ulnar collateral ligament in his right elbow on the eve of the season. After an ill-fated rehab attempt, he announced that he’d opted for Tommy John surgery.

It felt like a low point. The Padres' best pitcher ended up missing the entire season and a chunk of the next one. The rotation was thin behind him. It was going to be a long year on the mound.

Fast forward 15 months, and Lamet is slated to return Thursday for the series opener at Dodger Stadium. The vibe is certainly different.

Lamet will join a host of young rotation arms who have emerged as building blocks in San Diego. The Padres are on the fringe of Wild Card contention, and they entered July with a winning record for the first time in nine years. The future is undoubtedly bright.

And now they're welcoming Lamet back into the fold. Here are four effects of Lamet's return.

1. The rotation just got better

The Padres' rotation has probably overachieved a bit. A year ago, they posted the worst starters ERA in the National League. This year, they're in the middle of the pack at 4.35, a jump to 14th in the Majors and eighth in the NL without any acquisitions.

No question, Lamet's presence makes the group better. How much better? That depends on which version of Lamet they get. During his rookie season, Lamet could be erratic. But when he was good he was really, really good. Lamet struck out 139 hitters in 114 1/3 innings, the highest single-season Ks/9 for any starter in franchise history.

Since then, Lamet has bulked up, and he's added a tick or two to his fastball. During his six rehab starts, his heater sat in the mid-to-high 90s, and his slider was filthy as ever. Lamet is still toying with a curveball, and he has a changeup as well. But he probably won't need to use them much to be successful.

2. There's serious competition for places

When was the last time the Padres had genuine in-season competition for rotation places? When was the last time they sent a big league caliber starter to Triple-A for performance reasons? Not in Andy Green's tenure, that's for sure.

The Padres have rotated between a five- and six-man staff this season. If they stay healthy through the All-Star break, they'll enter the second half with seven or eight rotation options.

Lamet, Chris Paddack and Joey Lucchesi seem secure (unless the need to limit Paddack's workload arises). Among Eric Lauer, Logan Allen, Matt Strahm and Cal Quantrill, only two or three places are available.

The message seems clear: Perform, or it's someone else's job.

3. Preserving Paddack and Strahm just got easier

Both Paddack and Strahm were limited significantly in 2018 as they returned from major surgeries. The Padres have monitored their workloads this season as a result. Neither has pitched with fewer than five days of rest.

That plan wasn't always so easy to execute in the first half. The Padres had to use spot starts from Minor Leaguers and bullpen days to accomplish it.

If the starters can stay healthy in the second half, it should be much more feasible to give Strahm and Paddack the appropriate rest. There's plenty of cover in the rotation -- enough that the Padres might decide to skip Strahm and Paddack once or twice to keep their innings count down.

“The more depth we get, the more opportunity we have to create the right environment for the guys who need rest,” Green said.

4. There might be a trickle-down to the bullpen

The Padres' biggest strength last season was their bullpen. It suddenly might be their biggest weakness. Kirby Yates has been fantastic, while Craig Stammen, Luis Perdomo and Trey Wingenter have been serviceable. After those four, it's been a struggle, to say the least.

Lamet's return might help the Padres find their answer. They've already used Quantrill as a swing man between the rotation and the 'pen, and he's thrived in that role. Another rotation arm or two might join him.

“We're trying to find the right grouping to make us as good as we can be,” Green said. “If that means some of the guys that people see as starters go to the bullpen, and that gives us a better chance to win, so be it.

“We aren't married to the idea that in order to create the ideal environment for every young guy, they have to be in the rotation. It might be great for some of these guys to come out in three-inning bursts out of the 'pen at times. We want to be open to it.”

Strahm, who posted a 2.05 ERA in 41 appearances out of the 'pen last season, has proven to be a very capable reliever. If it's not him, perhaps Lauer or Allen could be similarly effective.

"Our best pitchers need to be here, whether they're in the rotation or in the bullpen," Green said.