The Giants have played 72 games (winning 45) and have 90 remaining. They have completed 4/9 (about 44%) of their season. Here's the tally so far:
1st inning: 8-10
2nd inning: 10-8
3rd inning: 15-3
4th inning: 12-6
You have to like 27-9 (.750) over the last two innings! Overall the club has the third-best record in baseball behind the Cubs and the Rangers. Their 5-1/2 game lead is also the third-best.
The Giants are scoring 4.57 runs per game, that's 11th of 30 teams and a few nicks above the 4.40 league-wide average. The Giants are allowing 3.71 runs per game which is fifth-best behind the Cubs, Mets, Dodgers, and Nationals. Those five teams have the best records in the NL--big surprise. If the Giants can continue to pitch well they should be in good shape for the rest of the season.
FanGraphs projects the Giants to finish 93-69 and gives them a 62% chance to win the division, just in case you were interested.