On appeal, the NLRC affirmed the decision of the POEA.iv[4] Its motion for reconsideration having been denied, petitioner filed the instant petition. More appropriately phrased, the issue for our consideration is whether or not the NLRC committed grave abuse of discretion in affirming the judgment of POEA finding private respondents dismissal to be illegal. Petitioner contends that public respondent committed grave abuse of discretion in not considering the several just causes that led to the dismissal of private respondent, and in not finding that the dismissal was for cause.v[5] This petition essentially raises a factual issue. We have consistently ruled that resort to a judicial review of the decisions of the NLRC in a petition for certiorari under Rule 65 of the Rules of Court is confined only to issues of want or excess of jurisdiction and grave abuse of discretion. It does not include an inquiry as to the correctness of the evaluation of evidence which was the basis of the labor tribunal in determining its conclusion. It is not for this Court to re-examine conflicting evidence, re-evaluate the credibility of the witnesses nor substitute the findings of fact of an administrative tribunal which has gained expertise in its specialized field. Thus, factual findings of the Labor Arbiter and the NLRC are entitled to due respect and even finality if supported by substantial evidence.vi[6] As revealed by the records, we find that the NLRC judgment sustaining the ruling of the POEA has sufficient factual and legal bases. Thus, there is no cogent reason to set aside the findings and the judgment of the Commission. It is settled that while probationary employees do not enjoy permanent status, they are entitled to the constitutional protection of security of tenure. Their employment may only be terminated for just cause or when they fail to qualify as regular employees in accordance with reasonable standards made known to them by their employer at the time of engagement,vii[7] and after due process.viii[8] There is no dispute that private respondent was dismissed from the service during his probationary period of employment. As stated in the repatriation letter, he was dismissed for failing to qualify for the position he occupied. Unfortunately, petitioner did not prove that private respondent was properly apprised of the standards of the job at the time of his engagement. Neither was it shown that private respondent failed to meet such standards. To justify private respondents dismissal, petitioner relied on the affidavit of Mr. Greco, executive manager of SECON International, claiming that private respondent was thoroughly briefed about his duties as group leader, first, in Manila by Mr. Greco, and then at the jobsite by Mr. Obsina whom private respondent was going to replace. But the POEA found such document of inconsequential value, for it was prepared long after the dismissal of private respondent and after the complaint for illegal dismissal was instituted. In rejecting said document, the POEA also observed that the allegations contained therein contradicts the tenor of a letter of Mr. Greco, affiant himself, addressed to private respondent instructing the latter to read the papers of Mr. Obsina to acquaint himself with the work of a group leader.ix[9] Private respondent thus appeared lacking adequate briefing about his duties, otherwise such instruction would be unnecessary.