The Cubs had contended for the NL East title for a time in 1977 and 1978 with teams that weren’t really that good, and both faded late in the year.
They did the same in 1979. After a poor start — they were 20-25 at the end of May and 9½ games out of first place — they went on a 28-13 run before the All-Star break and began the second half just 2½ games behind.
Opening that second half at Wrigley Field against the Braves, they split the first two games of a three-game weekend series but gained a full game in the standings.