Earlier this week, I looked at some of the arms emerging on the waiver wire here in September.

Today, it's mostly bats. They matter, too, you know.

The trick is figuring out who's getting regular playing time this time of year, with rosters expanded, which is easier said than done. Many of the call-ups themselves are only getting their feet wet, after all. For contenders, though, it's more straightforward. Those who perform get to play.

And then you have those players who just slip through the cracks. Yes, even five months in, we're capable of being surprised.

2017 season

.310 BA13 HR.941 OPS203 AB

Take Jose Martinez, a Cardinals bench bat who has typically made the most of what chances he has gotten. That's certainly true over his past three games, during which he has doubled three times and homered three times, including two Tuesday. Though he stands tall (6-foot-6) at the plate, strikeouts aren't a real issue for him, and even more impressive than the power is the pure hitting ability. His line-drive rate of 25.3 percent would rank in the top 10 if he had the at-bats to qualify. With Jedd Gyorko injured, forcing Matt Carpenter across the diamond, first base appears to be Martinez's for the foreseeable future.

Last 17 games (since DL return)

.371 BA3 HR3 SB1.008 OPS

Kevin Kiermaier fractured his hip in early June and didn't make much of an impression before then, undermining his sleeper potential. But over his past 143 games -- split between two seasons, of course -- he has hit .273 with 17 home runs and 28 stolen bases, making him sort of like Whit Merrifield but without the second base eligibility. Particularly if you need stolen bases, you won't find much better on the waiver wire.

2017 season

Trey Mancini BAL LF
.292 BA23 HR.843 OPS452 AB

Trey Mancini is hot again, batting .355 (22 for 62) with two home runs and an .889 OPS over his last 15 games. His ownership has never risen above 68 percent in CBS Sports leagues even though ... well, just look at his numbers. Even in a time of hitter surplus, he earns high marks for consistency, his only real slump lasting all of three weeks at the start of August. An owner with championship aspirations can feel good about slotting the 25-year-old rookie into his lineup.

2017 season (majors)

.260 BA15 HR131 AB44 K

Need homers? Matt Olson is the pickup for you. After  hitting 23 homers in the minors, he has hit 11 in 24 games since returning the the big leagues in August, including seven in his last eight. He's a little all-or-nothing for my tastes and may sit against the occasional left-handed pitcher, but for being just 19 percent owned, he can make up a lot of ground in that one category over a short period of time.

Tuesday at Athletics

3 1/3 IP4 H1 ER3 K

Let's sneak in a pitcher, shall we? Garrett Richards returned from a five-month absence for a strained biceps Tuesday, and though the outing was as short as you'd expect, he looked good, recording a swinging strike on seven of his 52 pitches and topping out at 98 mph. He should last longer with each subsequent start and as of now is in line for two starts in Fantasy Week 24 (Sept. 11-17). Though beset by injuries the past couple years, he still has an ace profile.

Last 61 games (minors)

.285 BA13 HR.929 OPS.313 BABIP

One of the few September call-ups who could make an honest-to-goodness impact in mixed leagues, J.P. Crawford got a start at third base Tuesday, but it's shortstop where you'll want to use him and where he'll probably play the most. A fixture near the top of the prospect rankings over the past few years, he finally began to generate some results with his high-contact swing during his last 2 1/2 months in the minors and has the potential to perform like a top-10 option at a weak position the rest of the way.