The 2015 season was largely a positive one for the Twins, and on Monday we touched on five of the most encouraging developments that took place.
 
It wasn't all sunshine and roses, though. So today we'll look at the five most unfortunate things that transpired this year, from a big-picture perspective.
 
1. Joe Mauer's decline continued
 
We hoped that he would regain some of his diminished sharpness and plate discipline as he moved away from his concussion issues. We hoped the transition to first base would result in improved power numbers driven by stronger legs. We hoped that Mauer could return to being a star-caliber player whose veteran bat would be the centerpiece in an athletic young lineup.
 
It hasn't happened. It's getting harder to believe it's going to happen.
 
The 2015 season marked the first time that Mauer has ever posted an OPS+ below 100, ending a string of 11 consecutive above-average offensive performances dating back to 2004. He batted .265. He slugged .380 with 10 home runs from a power position. He struck out almost twice as often as he walked.
 
His outstanding numbers with runners in scoring position prevented him from being a total liability, but with the bases empty (59 percent of his plate appearances) Mauer hit .232/.284/.349, while always batting at the top of the order. Throughout his career, he has made up for his lack of home run pop by being an on-base machine who consistently set up the hitters behind him for success. He didn't do that this year, and with a lack of injuries or limiting circumstances to point at, this is beginning to look like what Mauer truly is at age 32: a mediocre hitter who belongs closer to the bottom of the lineup than the top.
 
For better or for worse, Mauer – still owed $23 million annually through 2018 – is going to be around for a while yet. We can only hope for better.
 
2. Josmil Pinto basically dropped out of the catcher conversation
 
Pinto's receiving skills have long been considered marginal at best, but he nonetheless entered this season as the Twins' best hope for an eventual Kurt Suzuki replacement at catcher who could actually deliver some offensive punch. The hitting ability was there, so it was just a matter of making enough improvements defensively behind the plate in order for the Twins to entrust him with handling the pitching staff.
 
Unfortunately, Pinto endured a very rough season that likely ends any real possibility of him becoming a regular backstop for the Twins. He battled ongoing concussion issues throughout the summer that cost him two months and limited him to 72 total games (in which he posted an ugly .669 OPS). After returning to Rochester in August, he played DH exclusively the rest of the way.
 
When you combine the brain injury concerns with the iffy defensive abilities, it's increasingly difficult to imagine the Twins giving Pinto any kind of real shot to become their starting catcher, and that's a shame because no one else in the organization offers his kind of offensive upside at the position. That remains true even after the acquisition of John Ryan Murphy.
 
3. Glen Perkins fell apart in the second half
 
Perkins' tailspin at the end of the 2014 season was a little worrisome, but he seemingly erased any doubts with a first half in 2015 that saw him convert every save chance while earning on All-Star nod.
 
However, his quick and shocking drop-off after the break, and especially his costly poor outings late in the year, created some major question marks about his outlook going forward.
 
Two springs ago, the Twins handed Perkins an extension through the 2017 season with hopes that he'd be their closer for the duration of that term. Now, Terry Ryan is reluctant to commit to Perk as the ninth-inning man for 2016, and no one can blame him. The lefty was consistently ineffective for the final two months this year. After the All-Star Game, he never put together three consecutive appearances without allowing a run. Opponents batted .360 against him with seven home runs.
 
Given that Perkins has now tailed off in the late stages of back-to-back seasons, could this be an issue of preparation and conditioning? Ryan seemingly intimated such with this answer in his Offseason Handbook interview:
 
 
If that's the case, the problem at least seems correctable. Perkins doesn't strike me as the type of guy who's going to sit back and tolerate this kind of performance from himself, so perhaps his heartbreaking finish in 2015 will serve as a wake-up call.
 
4. Alex Meyer unraveled 
 
When the Twins traded Denard Span to the Nationals back in 2012, they acquired a player that they viewed as a potential front-end starting pitcher. Meyer cultivated his ace-in-waiting status during his first couple years in Minnesota's system, putting up huge strikeout numbers while shutting down minor league hitters at Double-A and Triple-A.
 
This year, however, everything came undone. Meyer floundered in the International League, which he had dominated in 2014. From spring training through September, the big right-hander constantly struggled to find the strike zone... and his confidence.
 
It's far too soon to give up on the 25-year-old Meyer. But it might be time to give up on the idea of him as a starter.
 
With his command issues and resulting huge pitch counts, he had an uphill climb in order to break into the rotation for a Twins team that values efficiency and deep outings from starters. He spent most of this season in the bullpen and it's looking like that is where his future lies.
 
The good news is that he can be a major asset there, with triple-digit heat and a wipe-out breaking ball. The bad news is that removing him from the rotation equation leaves the Twins system very thin on high-ceiling starters that miss bats.
 
5. Oswaldo Arcia stopped hitting
 
Over the years, Arcia has exhibited some notable downsides – namely, a dreadful lack of range in the outfield and some boisterous mannerisms on the field that tend to rub some people the wrong way. He has made up for these things, however, by consistently hitting the crap out of the ball.
 
Arcia rose fast through the minors, clobbering the competition at each stop, and reached the big leagues at age 21. He has accumulated a .741 OPS with 36 home runs in 853 MLB plate appearances, all before turning 25, becoming one of the most accomplished hitters in the game for his age. He looked like a long-term fixture in the middle of the lineup.
 
Arcia was beginning to heat up after a slow start this year before landing on the disabled list in May. He headed to Triple-A after being reinstated, seemingly for a temporary rehab stint, but never returned to the Twins.
 
At Rochester, Arcia's bat went amiss for the first time in his career. Outside of a brief home run flurry in July, he was inexplicably flat-out awful against Triple-A pitching for a full three months, batting just .199 with a .630 OPS while showing almost no plate discipline.
 
His lost year puts the Twins in a tough position, because Arcia will be out of options next spring, meaning he'll either need to be rostered or exposed to waivers. It's tough to count on him after his brutal showing in 2015, but it'd be even tougher to simply let his potent lefty power bat slip away.