The Penguins' offseason game plan: Additions needed on D

It's never fun to lose a playoff series, but given that most of the roster is already signed through 2018-19 (at least), the Penguins should be a top Cup contender again next season. Charles LeClaire-USA TODAY Sports

As each NHL team is eliminated from playoff contention -- either mathematically or by losing in the postseason -- we'll take a look at why its quest for the Stanley Cup fell short in 2017-18, along with three keys to its offseason and a way-too-early prediction for what 2018-19 will hold.

What went wrong

There's a reason no team has won three straight Stanley Cups in more than three decades. Sustaining success is a tough feat in today's salary-cap era.

The extra hockey -- Sidney Crosby had played in 48 playoff games in the past two Cup runs, which amounts to more than half of an NHL season -- certainly takes a toll. Credit GM Jim Rutherford for getting the Penguins close again. Sure, Rutherford had to part with significant team assets, such as center Nick Bonino and playoff performer Chris Kunitz, but he addressed one of the team's biggest deficiencies (depth centers) with a splashy trade acquisition of Derick Brassard.

Defense, though, remained a weakness, and the team did not replenish after shipping Ian Cole to Columbus at the deadline. Goaltender Matt Murray -- hampered by both injuries and coping with personal tragedy -- was strong but did not have his best season, nor postseason. (The 23-year-old also started just 45 games and appeared in only 49, the fewest by the Penguins' top goaltender in a decade.)

The Penguins began the season in a post-championship malaise, but they picked things up when it mattered -- and crushed the league with its scorching power play. Yet in the playoffs, injuries to key players lingered, and it felt like only one line (Crosby's, of course) was carrying the load.