When we looked (first) at second-half hitting peaks, we combined the 80s and the 90s. We won't do that here, as we want to utilize this post to emphasize the fact that the 1980s were the low point for top-notch offensive performances. For both first-half and second-half peaks, the 1980s produced only ten of each.
If you've been reading these posts consistently, you'll likely recall that George Brett had a monster second half in 1980 (you can see it at the top of this post). His injury-shortened second half in '83 didn't quite match up to that, but it was good enough to crack the Top 50 all-time. His more sustained run in the second half of '85 might have been more pivotal in ensuring that his Royals could win the AL West and eventually go on to win their first World Series championship.
Dwight Evans had the opposite scenario from Mike Schmidt in '81, starting out the year with a blistering pace, finally achieving the potential many had projected for him ever since he'd reached the majors.
The other three players in the Top 300 (as ranked by OPS+ or adjusted OPS) all had their hot first half performances in '87. Jack Clark was a first-half RBI machine helping the Cardinals to their third and final pennant under the guidance of Whitey Herzog; Eric Davis was possibly the most exciting player of the decade, with his combination of power and speed--all of it on display in abundance during the first half of '87; and Wade Boggs joined the uptick in homers peaking in that year to have a stellar first half en route to his finest overall season.
Some unexpected names here in the wake of adjustments to the ball and to the strike zone that were implemented after the '87 "homer spike." Mike Greenwell and Dave Winfield managed to thrive in the first half of '88 as many others struggled; they wound up #2 and #4 in the MVP voting that year, losing out to Jose Canseco.
Lonnie (Skates) Smith had always been a solid hitter (integral to the Cardinals' 1982 World Series run), and he was rejuvenated in '89 while with the Braves, ultimately hitting 21 HRs for the season (the only time in his career that he cracked double figures). Kevin Mitchell wound up with 47 HRs for the Giants in '89, leading them to an earthquake-interrupted World Series in which they were swept by their across-the-bay rivals.
Running numbers for this rather scarce assortment, we get the following breakouts: no .400+ BAs, with three with .350+ (Brett twice, Boggs) ; no .500+ OBP performances, but five over .450; one .700+ SLG (Brett), and six over .600. Of the ten players on the Top 300, one (Mitchell) hit 30+ HRs, with a total of three first-half performances cracking 20 HRs.