Cork South-Central is usually pretty predictable because it has a number of big-name Fianna Fáil, Fine Gael and Labour members.
Looking at the past results:
Micheál Martin usually tops the poll, and takes a second Fianna Fáil TD with him. For a time it was Batt O'Keefe, but in the last two elections it has been Michael McGrath.
Fine Gael have typically taken 1 - 2 seats, again with a well known name. The Fine Gael seat used to be Hugh Coveney's, and Simon Coveney (his son) took it in the by-election that followed Hugh's death. High profile candidates like Jerry Buttimer and Deirdre Clune have ensure that Fine Gael have been able to hold a second seat in the constituency.
More recently, there has usually been 2 Fianna Fáil seats, 2 Fine Gael seats and 1 Labour seat. Despite the backlash against Fianna Fáil at the last election, they still held their 2 seats, and I can see them holding both again this time around.
The only reason Sinn Féin got close to taking the last seat in 2011 was because of a combination of the backlash against Fianna Fáil, and the fact that the candidate they ran, Chris O'Leary, is a former Green party man who is a long-time councillor in Cork, and who is well known and respected locally. He is currently the Lord Mayor of Cork, so Sinn Féin have instead put forward the very young Donnchadh Ó Laoghaire - I don't think he will gain much traction. Sinn Féin tend to do much better in Cork North-Central, which is where they focus most of their efforts in the city.
All five incumbents are running this time around, and I would honestly be surprised if any seats changed hands. There has been aggressive opposition to Irish Water in parts of the constituency, including blocking of meter installations in some suburbs, but I don't think the dissatisfaction is widespread enough to have a meaningful effect on the outcome of the election.
If anyone were to suffer backlash for the actions of the current government, I would guess that it might be Ciarán Lynch (Labour). However, he is Labour's only candidate in the constituency, is well-liked in the area, and is reasonably visible in his work (having been a member of the banking inquiry, for example). I think it would be quite an upset if he were to lose his seat.
There just isn't enough of a chance for smaller parties to take a seat, so they rarely put much effort into the constituency. There is a reasonably large socio-economic divide between Cork South- and North-Central, with the result being that you tend to get a much greater diversity of "serious" alternative party candidates running and garnering votes in the latter. Cork then divides into what could be considered an "establisment" constituency (south) and an "alternative" constituency (north).
For example, I wouldn't be surprised to see Mick Barry take the last seat for the Socialist Party in Cork-North Central (he is well known and has been highly active locally for a number of years), and Sinn Féin are running second candidate there this time around, with serious intentions of capitalising on their polling gains and taking another seat.