When do we get a few changes to the periphery of the 25-man roster?
-- @510ProSports via Twitter

I can guarantee there will be at least one change this week. First baseman Matt Olson is finishing up his rehab assignment at Triple-A Las Vegas and could join the A’s as soon as Tuesday, when they return home for a three-game series with the Reds in Oakland.

As far as other moves on the horizon, with the starting rotation struggling to find consistency, Edwin Jackson and Daniel Mengden -- two key pieces from Oakland’s 2018 run to the postseason -- could find their way back to the A's in the next month. Jackson has pitched well in two starts in the Minors, while Mengden is 3-2 with a 3.00 ERA in six appearances (five starts) at Triple-A, holding opponents to a .205 batting average.

Who’s performing well with the Las Vegas Aviators and could expect a callup soon?
-- @stephenvstrex via Twitter

Skye Bolt was rewarded for his hot start at Triple-A with a callup over the weekend, and Jorge Mateo could be next.

Mateo is on fire in Vegas, seeing time at second base and shortstop, and he enters play on Monday batting .338 with a .944 OPS while leading the team with eight stolen bases, eight triples and eight doubles. He’s always been considered an electric player with all the tools necessary to become a Major League star, but the knock on him has been a lack of maturity and focus at times. Now 23 years old, Mateo appears to be putting it all together.

The club’s No. 8 prospect per MLB Pipeline, Mateo is already on the 40-man roster, so bringing him up would be an easy move.

Who are the vocal leaders on this team? Which players stand up and make speeches after games when things are going good or bad?
-- @ecarino68 via Twitter

As quickly as Matt Chapman is emerging as a star in MLB, his ascension in the clubhouse as a leader has been even faster.

Only in his second full season, Chapman has the attention of every player in the A's clubhouse. When he speaks, they all listen. If things are going well, he’s right there encouraging them to keep it going. When things are bad, he’ll stand up and look to get them back on track with a speech, like he did last week during Oakland’s three-game series in Boston.

There are other players who lead by example, like Marcus Semien and Khris Davis, but when it comes to a vocal leader, Chapman is the guy.

When will Jesus Luzardo return?
-- @flyeaglesfly510 via Twitter

Jesus Luzardo resumed throwing two weeks ago and is expected to begin pitching in Minor League games by the end of May. His Major League debut will likely depend on the state of Oakland's rotation by the time he’s seeing game action.

Fans have good reasons to be excited. The A’s top prospect posted a 0.93 ERA in Spring Training and has drawn comparisons to Johan Santana and Felix Hernandez. There’s a lot of pressure on him to step in and take over as a true ace, but the 21-year-old left-hander embraces the hype.

What is the A's plan for the young pitchers Jharel Cotton, A.J. Puk, Sean Manaea and Luzardo as they come back from injury? Are they looking at any of them as options for this year, or are they planning to play it safe and save them for 2020?
-- @JPowhatan via Twitter

All of them are options for 2019. Jharel Cotton has been throwing three-inning outings at extended spring camp, and A.J. Puk is believed to be on a similar schedule. Sean Manaea recently threw his first bullpen session over the weekend, and he’s targeting the All-Star break for a return to the A’s rotation.

I’d expect all four of these pitchers to be contributing by September at the latest. The A’s could use a boost to its pitching staff, and what better shot in the arm than four hard-throwing youngsters?

Any MLB ETA for Sean Murphy?
-- @drgriffin1897 via Twitter

The A’s received some tough news on Sean Murphy over the weekend when they learned he would need surgery to repair a torn meniscus in his left knee. That’s at least one month of recovery time for the A’s No. 3 prospect.

With defense that was already considered Major League-ready, the A’s were just hoping to see him put it together at the plate. He was off to a good start at Triple-A, slashing .324/.402/.459 over 19 games. If he recovers in a timely manner, a September callup is very much in play, if not sooner.

What is Franklin Barreto’s most likely fate at this point?
-- @itsdbax via Twitter

It’s been a rough start to the season for Franklin Barreto. He went from finishing third in Venezuelan Winter League MVP voting, to the A’s top hitter in Spring Training, to earning a spot on the Opening Day roster, only to be sent down to Triple-A before first pitch on that day as Oakland traded for veteran first baseman Kendrys Morales to fill in for Olson.

Barreto is off to a slow start in Vegas, batting just .214 through 26 games, although he showed a sign of promise by going 3-for-4 on Sunday. He’s a guy who A’s fans have clamored for to get a chance at regular playing time in the Majors for a couple of years now, but the organization seems to think he’s been exposed in his time with the big club and would like to see him work on consistency at Triple-A. It’s tough to get a gauge on his overall standing with the organization because there are some split opinions on him, but I think they all recognize the talent he has. It’s going to be on him to force his way up, and it starts with improving those low numbers he’s currently posting in the Minor Leagues.