THIS summer is proving difficult to predict in terms of on-field success for Yorkshire.

The champions have all bases covered in their squad ahead of the LV= County Championship title defence, which kicks off against Worcestershire at New Road this Sunday.

It is just unfortunate that the squad has been severely hit by international call-ups for the first month.

Coach Jason Gillespie has to do without Jonny Bairstow, Gary Ballance, Adam Lyth, Liam Plunkett, Adil Rashid and Joe Root for the first three matches because of England's tour to the Caribbean.

And if that wasn't enough, he also has to find a replacement batsman for captain Andrew Gale for the Worcestershire opener.

Gale is serving the last match of his ECB ban for improper conduct following last September's infamous spat with Lancashire's Ashwell Prince.

Alex Lees will almost certainly lead the side, having done so during the champion county fixture in Abu Dhabi, which Yorkshire won by nine wickets against the MCC.

Last year, this writer had a few quid on Yorkshire for Championship glory, alongside them for the Royal London One-Day Cup.

This season, I am not so sure. I still fancy a limited-overs title, although I haven't yet nailed down which one.

They have the firepower to win either or even both – Aaron Finch and Glenn Maxwell combining in Twenty20 is a mouthwatering prospect – with the signs looking good thanks to success in the Dubai Emirates Airline T20 event last month.

In terms of four-day success, there is a huge question mark, however.

The first month will be crucial. It would be surprising to see six players unavailable all at once due to home internationals, so there will be some breathing space from May onwards.

But they have to get over matches against Nottinghamshire and Warwickshire before the end of April, and results in those could have a massive bearing on the rest of the campaign.

Even without those aforementioned players, the squad still boasts significant experience.

The pace bowling attack is unaffected. Jack Brooks was the second leading wicket-taker in Division One in 2014 with 68, while Ryan Sidebottom, Steve Patterson and Tim Bresnan are all key performers.

Andrew Hodd and Rich Pyrah are valuable squad members who are set to be leant on heavily early on at least, while India Test batsman Cheteshwar Pujara, 27, will fill the early-season overseas duties.

Australian Finch will take over from him from late May through until late August before Kane Williamson wraps up the season.

The White Rose remain the favourites to retain their crown, and the bookies are more often right than wrong. I am erring on the side of agreeing.

But the youngsters must continue to stand up to first-team cricket or, in Jack Leaning's case, added responsibility.

Will Rhodes, Karl Carver and Matthew Fisher are all set to play a significant amount of first-team cricket in 2015.

It may be tougher than last year, but it is still realistic to expect more silverware at Headingley.