After a 98-loss season where they finished 40 games behind the National League West champion Los Angeles Dodgers in 2017, the San Francisco Giants have had an active offseason in hopes of being competitive in 2018.
Although the Giants tried to address their main weakness, offensive production, they don't look as if they will challenge anyone in the wildly exciting NL West. Instead of obtaining young players who could mature into fantastic superstars soon, they obtained via trades aging veterans who saw their better days behind them. Apparently, the Giants couldn't attract any free agents who could fill their holes.
From 2010-14, the Giants won three World Series championships. In 2016 even with a weak bullpen, the Giants went to the NL Division Series, losing to the eventual World Series champion Chicago Cubs. Since the All-Star break of 2016 when the Giants had the best record in in the Majors, they have had the worst performance in baseball.
What happened to the Giants?
The Giants became old. Although most teams with World Series aspirations have many experienced players, they also have youthful enthusiastic players. The Giants have a nucleus of Buster Posey, Brandon Belt, Brandon Crawford, and Madison Bumgarner. Bumgarner entering his prime years at 28 has performed with excellence since joining the team in 2009, but no one knows how well he will perform in '18. In May 2017, he suffered a major left shoulder injury while dirt biking in Colorado. In his 17 starts during the 2017 campaign, Bumgarner had a 3.32 ERA, but shoulder injuries can linger and decrease velocity and effectiveness.
There's no question since 2010 Posey has been the best player for the Giants. A 30-year-old catcher can do it all but catching is the most demanding position on the diamond. To rest Posey without sitting him on the bench, Bruce Bochy plays Posey at first base. Posey doesn't want to abandon the catching position, yet it would be in the Giants' best interest to convince him to do so.

The Giants envisioned Belt as a super left-handed power-hitting first baseman. However, it hasn't worked that way while Belt doesn't want to sacrifice his great on-base percentage to generate more power. During his career, Belt has suffered many concussions. The Giants might be better off to trade Belt.
At 29, Crawford is looking to rebound from a disappointing 2017 season where his offensive production wasn't up to his standards.
Needing an everyday third baseman and not willing to wait for Christian Arroyo to mature into a good third baseman, the Giants traded Arroyo to the Tampa Bay Rays for former-superstar Evan Longoria. There's no question that the Giants needed to upgrade their offense, scoring the second least runs in the NL in 2017. However, at 32, Longoria has seen his best baseball days behind him and had a low OBP in 2017. Although he had 20 homers in '17, he probably won't have this kind of power statistics in '18 since AT&T Park doesn't allow many homers.
Also, the Giants traded for Andrew McCutchen, a former face of the Pittsburgh Pirates organization. At 31, McCutchen has become a defensive liability in the outfield, and the Giants need good outfielders with good range since the stadiums in the NL West have spacious outfields. Despite winning a NL MVP Award in 2013, McCutchen's offense has declined. He is a good citizen and won the Roberto Clemente Award in 2015, but his impact on the Giants' '18 performance probably won't be major.

While the Giants' offense obviously needed to be improved, their eighth lowest ERA must be improved to be a factor in the NL West. AT&T Park doesn't allow many runs to be scored with its spacious dimensions and cool damp night air. So far, the Giants haven't done much to improve their pitching staff. The Giants traded the disappointing left-handed Matt Moore, who never performed well in a Giant uniform since being acquired by them at the 2016 non-waiver Trade Deadline from the Rays. On paper, the Giants' starting rotation looks satisfactory, but both Jeff Samardzija, 33, whose 4.42 ERA in 2017 was poor for a NL pitcher and Johnny Cueto, 31, whose 4.52 ERA in '17 was awful, have seen their best days behind them. The most intriguing starter for the Giants is Ty Blach.
The Giants don't have an effective bullpen even though their manager Bruce Bochy likes to use it often. They probably will begin the season without a closer since Mark Melancon, who underwent surgery last September to relieve symptoms of exertional compartment syndrome in his right forearm. Their primary left-handed reliever Will Smith is still recovering from Tommy John surgery.
There's no quick fixes for a team who lost 98 games. Will the Giants be better in 2018? Probably, but they likely won't go to the postseason.