Since The Break

Some tidbits about the Pirates since the All-Star break:

• They're 33-21, tied with the Cardinals and Rangers for the fourth-best record in all of baseball, trailing the Blue Jays (37-15), Mets (35-19), and Cubs (35-20). So yes, the four best records in the National League since the break are those of the Mets followed by the three top NL Central teams.
• Their starting pitchers have been mediocre: 4.18 ERA, ninth in the NL, and a 20-20 won-lost record. They've probably been somewhat unlucky, allowing the second-highest batting average on balls in play and the fifth-lowest strand rate (baserunners not coming around to score). Those both tend to be measures of luck more than skill. 
• The bullpen, though...3.12 ERA, third in the league, although helped by the third-highest strand rate in the league. Addressing the question of overuse, Pirates relievers have thrown the sixth most innings since the break but faced the seventh most batters and thrown the eighth most pitches--they've continued to be effective.
• The offensive has come alive. Seventh in the league in runs before the break, they're third since.

Looking at the offense, here are the team's hitters (minimum 40 plate appearances), ranked by OPS, since the All-Star Break.

Player	G	AB	R	H	2B	3B	HR	RBI	SB	CS	BB	SO	BA	OBP	SLG	OPS	H1	Diff
Jung Ho Kang	50	187	33	59	14	0	11	29	0	2	10	46	.316	.373	.567	.939	.732	+.207
Andrew McCutchen	52	189	37	58	9	1	10	36	2	2	34	53	.307	.415	.524	.939	.892	+.047
Mike Morse	28	43	5	14	3	1	1	4	0	0	5	12	.326	.408	.512	.920	NA	NA
Pedro Alvarez	51	140	20	36	4	0	11	28	1	0	14	50	.257	.327	.521	.848	.733	+.115
Francisco Cervelli	45	152	20	47	6	3	2	9	0	0	22	28	.309	.401	.428	.829	.766	+.063
Gregory Polanco	52	220	31	63	14	3	5	20	7	3	16	43	.286	.335	.445	.780	.653	+.127
Starling Marte	51	186	31	53	11	2	3	19	10	2	5	29	.285	.338	.414	.752	.784	-.032
Sean Rodriguez	47	84	12	25	6	0	1	7	0	2	2	24	.298	.337	.405	.742	.589	+.153
Aramis Ramirez	41	145	13	36	10	0	5	28	0	0	10	17	.248	.297	.421	.718	NA	NA
Neil Walker	52	176	21	42	7	3	6	25	0	0	18	28	.239	.299	.415	.713	.755	-.042
Josh Harrison	21	58	9	16	2	0	0	3	1	3	5	9	.276	.354	.310	.664	.696	-.032
Travis Ishikawa	28	48	4	12	2	0	1	8	0	0	4	16	.250	.308	.354	.662	NA	NA
Chris Stewart	22	49	1	14	0	0	0	7	0	0	2	9	.286	.308	.286	.593	.702	-.109
Jordy Mercer	20	58	4	12	2	0	0	6	0	1	7	14	.207	.288	.241	.529	.615	-.086

Provided by Baseball-Reference.com: View Play Index Tool Used
Generated 9/14/2015.

In the table, "H1" refers to the player's OPS in the first half of the season, i.e., up to the All-Star break. "Diff" is the difference between his second and first half OPS. For Morse and Ramirez, both of whom were acquired via trade after the break, the stats shown are only those accumulated with the Pirates. The league average OPS for position players in the second half is .736, so the dividing line between above- and below-average Pirates falls between Rodriguez and Ramirez.

A few things seem apparent from the table:

• The Pirates need Jung Ho Kang in the lineup. He's lost playing time to Aramis Ramirez at third and to Jordy Mercer at shortstop. He's been pretty clearly a better hitter than both, and only Mercer carries a notably superior glove. 
• There's been talk of platooning Polanco and Harrison in right. On paper, that makes sense: Harrison has a .718 OPS against left-handed pitchers, while Polanco's is just .555. But Polanco's been a different hitter since the break. His OPS against lefties was .356 (!) before the break, .707 since. Small sample warning--that .707 is based on only 55 plate appearances--but the difference between Polanco and Harrison against southpaws has been pretty small.
• Harrison's platoon advantage makes more sense to me at second, where Neil Walker has a .770 OPS against right-handed pitchers but only .597 against lefties.
• The platoon of Alvarez and Morse at first base is quite effective at the plate, though it's cringe-worthy in the field. 

So if I'm Clint Hurdle, here's whom I'd play:

C: Cervelli, with Stewart giving him a breather

1B: Alvarez against righties, Morse against lefties, Ishikawa as late-inning defensive replacement

2B: Walker against righties, Harrison against lefties

SS: Kang, Mercer as late-inning defensive replacement with Kang moving over to third

3B: Ramirez against lefties, Harrison and Ramirez splitting time against righties as the situation dictates

LF: Marte

CF: McCutchen

RF: Polanco

But seriously. Since Mercer returned from the disabled list on August 23, the Pirates have started Mercer at short and Ramirez at third in six of their 21 games, or 29% of them. They're 10-5 in games that Kang's started and 3-3 in games that he hasn't. I'm all in favor of getting players occasional rest, but this man's basically been Andrew McCutchen at the plate in the second half of the season. Get him in the lineup.