In Week 4 of the MLB season, numerous teams around the league turned to their farm system as they looked for an early-season spark. For fantasy baseball players, adding a top prospect early can pay dividends throughout the remainder of the season.

A top prospect is rarely called up to sit on the bench. If they're getting the MLB call, their teams are expecting them to be difference makers. Oftentimes, they'll immediately be put into starting situations. In fantasy baseball, landing a starter after the draft is a steal. This is especially true if that starter turns into fantasy baseball gold.

But even with all the call-ups, rookies aren't the only ones dominating MLB. Veterans across the league are proving that they have more than enough gas in the tank. They shouldn't be ignored in fantasy baseball.

Week 4 will present a lot of fresh faces making a name for themselves in MLB. As the league watches, many make up our top four fantasy baseball waiver wire pickups.

Brett Baty – 3B New York Mets

Brett Baty got his first cup of coffee with the New York Mets in 2022, appearing in 11 games. He hit just .184 with two home runs and five RBI. However, after a scorching start to the AAA season, the Mets have once again called Baty up. And it couldn't have come at a better time.

Over his first nine games, Baty hit .400 with five home runs, 15 RBI and two stolen bases. His call-up comes during starting third baseman Eduardo Escobar's slump. Escobar has hit a measly .114 with a home run and six RBI this season. He has more strikeouts (12) than hits (5).

With Escobar struggling, Baty could take over at the hot corner. The Mets wouldn't have called him up if they didn't expect him to play a role at third. If he takes over the starting role from Escobar, he has top-level potential at the cost of a waiver wire pickup.

Vaughn Grissom – SS Atlanta Braves

The Atlanta Braves made a similar decision with Vaughn Grissom. However, Grissom's call-up came after an injury to starter Orlando Arcia. With no other options, Atlanta turned to Grissom. A guaranteed role in the Braves' potent offense will be a fantasy baseball boon for Grissom.

Grissom played in 41 games during his rookie season in 2022. The shortstop hit .291 with five home runs, 18 RBI and five stolen bases in his debut. Since his call-up, Grissom has appeared in three games with the Braves. He has hit .308 with a double and two RBI. He had a crucial go-ahead hit in Atlanta's win over the Royals on Sunday.

As long as Arcia is out, Grissom will see playing time at shortstop. If he keeps producing, perhaps the Braves keep him there long-term. Grissom's bat and speed in the Braves lineup would do wonders off the fantasy baseball waiver wire.

Zach Neto – SS Los Angeles Angels

Like the two names prior on this list, Zach Neto was once a top prospect. However, his MLB call-up will lead to his big-league debut. The Los Angeles Angels didn't wait long to see what they have in Neto.

The Angels drafted Neto in thee first round of the 2022 MLB Draft. He played in just 44 games in the minors before reaching the MLB. Neto was tearing the cover at the ball this season at AA, hitting .444 with three home runs, 10 RBI and three stolen bases.

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It may take Neto some time to get up to MLB speed. That was evident in his Angels debut when he went 0-4 with two strikeouts. However, Neto packs serious potential. Playing alongside Mike Trout, Shohei Ohtani and Anthony Rendon should boost his fantasy baseball status.

Colin Rea – SP Milwaukee Brewers

Baty, Grissom and Neto – respectively – are the top three fantasy baseball waiver wire pickups for Week 4. Colin Rea has had a much different MLB journey than this week's top prospects. However, that doesn't mean Rea can't be valuable in fantasy baseball.

Prior to this year, Colin Rea last pitched in MLB in 2021 – ironically with the Milwaukee Brewers. He played for the Fukoka SoftBank Hawks in 2022. After his performance in Japan, the Brewers decided to give him another shot with a minor league contract.

In his 2023 debut, and his first appearance since 2021, Rea pitched 5.2 innings of one-run baseball in a no-decision against the San Diego Padres. He didn't allow a walk and struck out six.

Perhaps it was returner's luck for Rea. However, his impressive start will certainly earn him mor opportunities. With Brandon Woodruff out, Rea will have an opportunity to lock down a rotation spot at least for the time being. He's a waiver wire pickup that not many players knew of before the season. However, Rea's debut certainly showed promise.