Going into each season, we typically have a sense of which teams will have the best lineups and pitching staffs. But there are always some surprises along the way, and this year is no exception.

Here are seven units (offenses, rotations, bullpens) that are dramatically outperforming expectations in 2023. (Stats below are through Monday's games.)

1) Rays’ offense
As you might expect just from looking at Tampa Bay’s 23-6 record in 2023, the team has been firing on all cylinders, with an elite rotation, bullpen and offense. But while the Rays were always expected to pitch well this season, even the most optimistic observers couldn’t have predicted this type of offensive dominance. The club made no notable additions to its lineup after ranking 21st in MLB in runs scored last season. However, the Rays lead the Majors in runs per game and have a collective 148 wRC+ -- 29 points better than the next closest team. Ten Rays have hit at least four homers, led by Randy Arozarena, Yandy Díaz, Brandon Lowe and Luke Raley with seven apiece. Young outfielder Josh Lowe, who had a .627 OPS as a rookie in 2022, leads the club in average (.342), slugging (.632) and OPS (1.029).

2) Pirates’ offense
The Pirates have been the biggest surprise in the Majors this season, starting off 20-9 after back-to-back 100-loss campaigns. Pittsburgh owes a lot of its success to its offense, which is tied for fourth in the Majors in wRC+ and ranks fifth in runs per game despite losing promising young shortstop Oneil Cruz to a fractured left ankle. The Bucs have showcased an impressive combination of power and speed, tying for first in the NL in extra-base hits while also leading MLB in stolen bases. The team’s starting outfield of Bryan Reynolds, Jack Suwinski and Connor Joe has been especially potent, and Andrew McCutchen has had a renaissance in his return to Pittsburgh.

3) Pirates’ rotation
We also need to give some props to Pittsburgh’s starting staff, which has been a major source of consistency for the club. With free-agent additions Vince Velasquez and Rich Hill joining holdovers Mitch Keller, Roansy Contreras and Johan Oviedo, the Pirates lead all teams in quality starts (18) and rank ninth in rotation ERA. A year ago, the Bucs had MLB’s seventh-highest rotation ERA and ranked 28th in quality starts. The Velasquez signing has worked out particularly well -- the right-hander has posted a 3.06 ERA through six starts after notching an ERA north of 5.00 for three teams over the previous six years.

4) Cubs’ offense
The free-agent additions of Dansby Swanson and Cody Bellinger have worked out better than the Cubs could have ever imagined in 2023, with Swanson recording a career-high .419 on-base percentage and Bellinger rediscovering his MVP form. Bellinger, who was non-tendered by the Dodgers after putting up a .611 OPS across 2021-22, has hit .295 with seven homers and a .962 OPS over his first 25 games with Chicago. Meanwhile, the Cubs have gotten excellent production from holdovers such as Nico Hoerner, Ian Happ, Patrick Wisdom and Yan Gomes, contributing to the highest-scoring offense, on average, in the NL.

5) Rangers’ offense
Given the money they spent on Jacob deGrom, Nathan Eovaldi, Andrew Heaney and Martín Pérez in free agency, the Rangers’ playoff hopes seemed likely to hinge on the performance of their starting rotation. But the biggest reason for the club’s 17-11 record is its offense, which ranks second in the Majors in runs per game and wRC+ despite the loss of shortstop Corey Seager to a strained hamstring on April 11. Jonah Heim and Josh Jung have stepped up in Seager’s absence, teaming with Marcus Semien, Adolis García and Nathaniel Lowe to give Texas five regulars performing at a high level. Those five have combined for 28 homers, 115 RBIs and a 133 wRC+ so far.

6) Twins’ rotation
While Minnesota’s offseason trade for Pablo López and the return of Kenta Maeda from Tommy John surgery fostered optimism about the team’s rotation entering 2023, we didn’t see this coming. Although Maeda struggled before going on the IL with a strained right triceps, the Twins’ starting staff ranks second in the Majors in innings pitched, and only the Rays have posted a lower rotation ERA. The Twins also just shut down Tyler Mahle with a right elbow impingement, but they’ve gone 14-5 in games started by López, Sonny Gray, Joe Ryan or Bailey Ober -- a quartet that has combined for a 2.44 ERA over 19 starts.

7) Angels’ bullpen
The Halos’ bullpen hasn’t been perfect, blowing seven save chances and racking up 10 relief losses, but on the whole, the team’s relief corps is much improved compared to 2022. New addition Carlos Estévez has led the way, converting all six save opportunities and posting a 1.32 ERA, while fellow free-agent acquisition Matt Moore owns a 1.26 ERA over 14 1/3 innings. Estévez and Moore have helped the Angels record MLB's eighth-lowest bullpen ERA and fourth-highest reliever WAR total, one year after ranking 18th in ERA and 25th in reliever WAR.